JPS583524B2 - Manufacturing method of liquid crystal display cell - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a liquid crystal cell.

More specifically, a hole sealing method after filling liquid crystal into a container for a field-effect liquid crystal display cell which has an organic aligning agent in the part that contacts the liquid crystal and has a hole for filling the liquid crystal. Regarding.

Liquid crystal display cells, as light-receiving display components, have the characteristics of low power consumption, high contrast, and high response performance.In recent years, along with the development of electronic technology, they have been used in products such as wristwatches.
It has been applied to the display field of calculators and various measuring instruments, and currently, in addition to these practical applications, development of color, memory, low voltage, matrix display, multi-function display, etc. is progressing, and its application fields are also expanding. is currently being expanded.

Therefore, there is a strong demand for improvements in liquid crystal display cells to ensure stability in quality accuracy and high reliability as durable components.

However, the disadvantage of this liquid crystal display cell is that the liquid crystal material itself easily undergoes chemical or physical changes due to exposure to oxygen, light, water, etc., and is therefore subject to deterioration. This is a major point in obtaining highly reliable liquid crystal display cells.

In general, a field-effect liquid crystal display cell consists of two substrates on which a conductive film with a predetermined pattern is formed on one surface, and an organic material layer on which an alignment treatment is applied to give molecular orientation to the liquid crystal. In the case of a transmission type cell, both the substrate and the conductive film are transparent, and in the case of a reflection type cell, at least one substrate and the conductive film are transparent). The area around the gap is filled with 1 for liquid crystal filling.
A container for a liquid crystal display cell is produced by leaving one or two holes remaining and sealing them with a sealing material, filling the container with liquid crystal through the holes, and then sealing the holes.

Various organic and inorganic materials are being used for sealing liquid crystal display cells currently being developed, but the current situation is that no material with reliable and stable performance has yet been obtained.

In particular, regarding hole sealing, since the sealing operation is performed after the liquid crystal is filled into the container, it is necessary to take into consideration the effect on the liquid crystal and to completely seal the hole surrounded by the substrate and surrounding sealing material. This is the most difficult method, and no method for completely sealing the holes has yet been found in the laboratory.

In view of the above points, the present invention provides a hole sealing method for manufacturing field-effect liquid crystal display cells that is highly reliable and superior in terms of workability and cost compared to conventional methods. The purpose is to

For this purpose, the present invention provides plasma treatment for the pottery wall soil around the hole of a glass container for a liquid crystal display cell having a hole for filling the liquid crystal, and then coating the treated surface with a metal film consisting of three layers. The liquid crystal is filled into the container through this hole, and then a solder layer is formed on the metal film to seal the hole.

Soda glass, borosilicate glass, hard glass, etc. are used as the glass substrate material constituting the liquid crystal display cell container.

Crystalline or non-crystalline glass frit is used as a material for sealing the periphery of the gap between two glass substrates facing each other.

As the liquid crystal substance, nematic liquid crystals having positive anisotropy such as Schiff-type, ester-type, aso-type, azoxy-type, biphenyl-type, triphenyl-type, etc. alone or in combination, or the above-mentioned nematic liquid crystals having positive anisotropy can be used. A nematic liquid crystal having a negative anisotropy such as p-methoxybenzylidene-p'-n-butylaniline or p-ethoxybenzylidene-p'n-butylaniline is added to the liquid crystal to give an overall positive anisotropy. Mixtures of these materials, as well as systems in which cholesteric liquid crystals, various optically active organic compounds, and other additives are added, can be used.

Organic aligning agents for imparting molecular orientation to the filled liquid crystal include those having film-forming properties, such as polyvinyl chloride, polyvinyl acetate, polymethyl methacrylate, polystyrene, polyvinyl alcohol, polyvinyl butyral, and polymethyl cyanoacrylate. , polysulfone, polyimide, polyamideimide, polyesterimide, polybenzimidazole, polyamide, polyparaphenyl oxide, polycarbonate, polyacetal,
Polyethylene, polypropylene, cellulose resin, urea resin, melamine resin, phenol resin, epoxy resin, polyester, alkyd resin, urethane resin, resorcinol resin, furan resin, silicone resin, fluorine resin, etc., and copolymers thereof, etc. In addition, natural or synthetic polymers such as elastomers such as natural rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, polychloroprene, polybutadiene, polyisobutylene, polyisoprene, thiol rubber, polyacrylate, other ion exchange resins, and high surfactant. Molecular coagulants and the like are used alone or in a mixed system. After forming a film, they are oriented by rubbing in a certain direction with a cloth, brush, or the like.

The above-mentioned organic alignment agent can be applied as a solution by a spraying method, a dipping method, a spin coating method, a brush coating method, or the like, or a film can be formed on the substrate constituting the cell by means such as vapor deposition.

At this time, no matter how careful the operation is, contamination of the end face of the substrate by the organic alignment agent cannot be avoided, and the presence of the organic alignment agent adhering to this end face prevents the formation of a metal film as in the present invention.

That is, if an organic alignment agent is present between the substrate surface and the metal film, the metal cannot be firmly adhered to the substrate.

Therefore, after solder sealing, the solder and metal are likely to peel off together from the substrate.

Therefore, in the present invention, plasma treatment is performed before providing the metal layer on the sealing portion to remove the above-mentioned unnecessary organic alignment agent.

The plasma treatment uses oxygen plasma for ashing.

That is, it is carried out in the open air (containing about 1/5 oxygen), in an atmosphere of only oxygen, or a mixture of oxygen, water, alcohol, etc.

After the treatment with oxygen plasma for ashing, treatment with fluorine-based gas plasma for etching can also be performed.

Further, after the treatment with oxygen plasma, plasma treatment may be performed in a gas atmosphere containing a mixture of oxygen and fluorine gas, and it is also possible to perform plasma treatment from the beginning only under this mixed gas atmosphere.

When plasma processing is performed in an atmosphere containing a fluorine-based gas in this manner, the end face of the substrate in the sealed portion can be etched by a very small amount to expose a new uncontaminated end face of the substrate.

In this case, if the conductive film or other parts of the substrate are exposed to plasma, the conductive film is likely to deteriorate or disappear, so these parts are masked if necessary.

If the end surface of the substrate is newly exposed in this way, the adhesion between the substrate surface and the metal layer becomes very good.

Next, to form a metal film on the edge of the plasma-treated substrate,
Methods such as vacuum evaporation, sputtering, and ion plating are used.

As the solder, silver-containing solder, low melting point solder, and other ordinary solders having a melting point of about 150 to 450° C. can be used.

In particular, silver-containing solder is preferred because it has good weather resistance.

The material for the three-layer metal film is Cr and F, which have adhesive strength to glass and good weather resistance as the bottom metal.
E or Ti with a thickness of about 100 to 1000 Å, and Ni with a thickness of about 300 to 1500 Å, which has good solder adhesion strength and weather resistance, to the middle layer metal, is sufficient for soldering even if liquid crystal is interposed in the top layer metal. Au, Pi, Rh, Pd,
Use a hard-to-oxidize metal such as Ag.

With this configuration of the hole sealing part, the bottom layer metal maintains its adhesive strength with the glass, and this adhesive strength is greatly increased due to the plasma treatment, and the middle layer metal maintains its adhesive strength with the solder. The top layer metal has good wettability with solder to improve sealing properties, and all three metal layers have good weather resistance.

Therefore, (1) the working temperature and time range during soldering can be increased, and the soldering workability is improved; (2) the adhesion and adhesive strength of the three-layer metal film to glass and solder are improved; (3) Storage at 100°C for 1000 hours, 7
0°C, 90%RH (relative humidity), held for 1000 hours, 0
A weather resistance test consisting of 10 thermal cycles from .degree. C. to 80.degree. C. revealed no increase in current value, poor appearance, poor temperature characteristics, etc., and a long-life liquid crystal display cell was obtained.

The present invention will be explained in detail below using examples.

Embodiment 1 FIGS. 1 to 3 show the manufacturing process of the present invention, where FIG. a is a side view, and FIG. b is a side view, and FIG. It is a CC sectional view.

As shown in FIG. 1, two glass substrates 3 and 4 each having a transparent conductive film 1 and 2 with a predetermined pattern formed thereon are oriented with polyimide polymers on the surfaces where the conductive films 1 and 2 are located. The alignment layers 5 and 6 of the substrates 3 and 4 are placed opposite to each other with a predetermined distance between them, and the periphery of the gap between the opposing substrates 3 and 4 is formed in a low-temperature manner, leaving a hole 7 for filling the liquid crystal. It is sealed using a melting point glass frit 8 to produce a liquid crystal display cell container 9.

Next, as shown in FIG. 2, the liquid crystal display cell container 9 was fixed in a plasma chamber, and the area around the hole 7 on the side thereof was heated at an oxygen flow rate of 100 cc/min, 1 mmHg, and 20
After plasma treatment for 10 minutes at an output of 0 W, a Cr layer 10 with a thickness of 500 Å, a Ni layer 11 with a thickness of 700 Å, and an Au layer with a thickness of 500 Å are formed on the treated surface by vacuum evaporation (vacuum degree 2 × 10 -5 Torr). 12 into a predetermined shape, Schiff-based Np liquid crystal 13 is filled into container 9 through hole 7 by a vacuum method.

In this case, it is more convenient if a metal layer is also formed near the entrance of the hole 7.

For this purpose, oblique vapor deposition may be performed while rotating the container 9.

Furthermore, as shown in FIG. 3, a solder layer 14 is formed using a soldering iron from the periphery to above the hole 7 so as to seal the hole 7 of the Au film 12.

In this case, it is not necessarily necessary to solder the entire surface of the Au layer 12, but it is sufficient to solder enough to fill the holes 7.

The obtained liquid crystal display cell was subjected to a weather resistance test as described above, and as a result, it was found that the cell had good weather resistance, with no decrease in NI point, no increase in current value, and no defective appearance.

The following four types of polyimide polymer coatings were prepared, and the coatings were rubbed with cloth or a brush for orientation treatment. After that, cells were manufactured as described above, and the results described above were obtained for each of them. Ta.

(1) A 1% N-methylpyrrolidone solution of polyamic acid, which is a precursor of polyimide obtained by condensing pyromellitic anhydride and 4,4' diaminodiphenyl ether, is applied to one side of the substrate by spin coating. 3 at 250℃.
Heat treatment was performed for 0 minutes to cause dehydration and ring closure, thereby providing a polyimide film.

(2) A 0.5% dimethylacetamide solution of polyamic acid, a precursor of polyimide obtained by polyaddition of hyromellitic anhydride and 4,4'-diaminodiphenylmethane, was applied to the substrate by spin coating. Apply on one side of the
A polyimide film was formed by heat treatment at ℃ for 30 minutes to cause dehydration and ring closure.

(3) A 3% dimethylacetamide solution of polyamic acid, which is a precursor of polyamideimide obtained by polyaddition from 3.3' di, aminobenzanilide and pyromellitic anhydride, is applied to the substrate by a dipping method, and It was heated at ℃ for 1 hour to cause dehydration and ring closure, thereby providing a polyamideimide coating.

(4) Polyamic acid, a precursor of polyesterimide obtained from dicarboxylic anhydride obtained from hydroquinone and trimellitic anhydride, and 4,4'-diaminodiphenyl ether, is spray-coated on a substrate, and heated. A polyesterimide coating was provided by dehydration and ring closure.

Example 2 After plasma treatment was performed on the periphery of the hole of a liquid crystal display cell container similar to Example 1, which had been subjected to orientation treatment using poly α-amino acids, sputtering method (vacuum degree 2 X10-5 Torr, thickness 300
Cr layer with thickness of Å, Ni layer with thickness of 500 Å, A layer with thickness of 300 Å
After forming the G layer, ester liquid crystal is filled into the container through the hole.

Next, this container was immersed in a solder bath to form a solder layer on the entire surface of the Ag layer, and then a mixed liquid crystal obtained by adding triphenyl liquid crystal to biphenyl liquid crystal was filled, and the holes were opened in the same manner as in Example 1. I did the sealing.

The obtained liquid crystal display cell was subjected to weather resistance tests similar to those in Example 1, and passed these weather resistance tests.

Example 3 After plasma-treating the periphery of the hole of a liquid crystal display cell container similar to Example 1, which had been subjected to orientation treatment using a fluorine-based resin, a thick layer was applied to the vessel wall soil using a vacuum evaporation method. 200 Å thick Ti layer, 1000 Å thick Ni layer, 50 Å thick
After forming a 0 Å Au layer, azoxy-based and ester-based mixed liquid crystal is filled into the container.

Then, the hole was soldered using a low-temperature soldering iron to seal the hole.

The obtained liquid crystal display cell was subjected to weather resistance tests similar to those in Example 1, and passed these weather resistance tests.

Example 4 After plasma-treating the periphery of the hole of a liquid crystal display cell container similar to Example 1 having a coating treated with orientation treatment of polyoxyethylene nonyl phenyl ether, the surface of the container wall was treated with plasma in the same manner as Example 1. By ion plating, the thickness of 5
00 Å Ti layer, 700 Å thick Ni layer, 500 Å thick
After forming the Ag layer, the container is filled with Schiff-based and biphenyl-based mixed liquid crystal.

Next, the container is immersed in a solder bath containing 3.0% silver-containing solder to form a solder layer on the entire surface of the Ag layer to seal the holes.

When the obtained liquid crystal display cell was subjected to weather resistance tests similar to those in Example 1, it passed these weather resistance tests.

From the above detailed description, it is clear that according to the present invention, a liquid crystal display cell with excellent weather resistance can be obtained with good workability.

[Brief explanation of drawings]

FIGS. 1 to 3 are explanatory diagrams of manufacturing steps of an embodiment of the present invention. In the figure, 1, 2... conductive film, 3, 4...
...Glass substrate, 5,6...Organic alignment agent layer,
7... Hole of container for liquid crystal display cell, 8...
・Peripheral sealing material, 9... Container for liquid crystal display cell,
10...Cr layer, 11...Ni layer, 1
2... Au layer, 13... Liquid crystal, 14...
...Solder layer.

Claims (1)

[Claims] 1. An organic aligning agent is provided in the part in contact with the liquid crystal, and after filling the liquid crystal into a field-effect liquid crystal display cell container having a hole for filling the liquid crystal, the hole is sealed and the liquid crystal is filled. In the method of manufacturing a display cell, after plasma-treating the vessel wall soil around the hole of the container which is not filled with liquid crystal, a first metal layer made of Cr, Fe or Ti, and a first metal layer made of Cr, Fe or Ti are sequentially applied to the treated surface.
a step of forming a second metal layer consisting of i and a third metal layer consisting of Au, Pt, Rh, Pd or Ag, a hole in the container and a hole formed in the three metal layers continuous to the hole; A method for manufacturing a liquid crystal display cell, comprising the steps of: filling the container with liquid crystal; and soldering onto the third metal layer to seal the hole.