JP2005221944A - Manufacturing method of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a liquid crystal display device of a liquid crystal dropping and bonding method, which is weak to light among components of the liquid crystal display device by curing a sealing material only by heating without using light. It is possible to manufacture a high-quality liquid crystal display device by avoiding troubles in elements.
A liquid crystal display having a step (P18) of forming a sealing material on a substrate, a step (P5) of dropping a liquid crystal on the substrate, and a step (P21) of bonding a pair of substrates in a vacuum environment. It is a manufacturing method of an apparatus. The bottom point in the time-viscosity curve of the material constituting the sealing material is set to a viscosity value that does not cause a seal pass between the liquid crystal and the sealing material when the sealing material is thermally cured. The bottom point is set to a viscosity value that does not cause misalignment between the pair of substrates when the sealing material is thermally cured.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a liquid crystal display device of a liquid crystal dropping and bonding method.

  In general, a liquid crystal display device is formed by bonding a pair of substrates with a sealing material and enclosing liquid crystal in a gap formed between the substrates, a so-called cell gap. At this time, in the conventional method of manufacturing a liquid crystal display device, an opening for injecting liquid crystal is formed in a part of the sealing material, and a pair of substrates are bonded to each other with the sealing material to form a panel structure. The liquid crystal was injected into a region surrounded by the sealing material through the opening provided in a part of the material, that is, a cell gap.

  In contrast to such a conventional method for manufacturing a liquid crystal display device, a method for manufacturing a liquid crystal display device called a liquid crystal dropping and bonding method has recently been proposed. In this manufacturing method, an annular sealing material having no liquid crystal injection opening is formed on at least one of the pair of substrates, and a necessary amount of liquid crystal is formed in a region surrounded by the sealing material or in a corresponding region of the other substrate. Are dropped, and then the substrates are bonded together to form a liquid crystal panel. That is, according to this manufacturing method, when the bonding of the pair of substrates is completed, the liquid crystal is sealed in the cell gap (see, for example, Patent Document 1).

  By the way, in the manufacturing method of a liquid crystal display device of a liquid crystal dropping and bonding method, when a pair of substrates holding a liquid crystal is released under atmospheric pressure, the liquid crystal expands between the pair of substrates. At this time, if the sealing material cannot withstand the expansion force of the liquid crystal, the liquid crystal leaks out of the liquid crystal panel. This phenomenon is called a seal pass. In order to prevent the generation of this seal pass, the strength of the seal material must exceed the expansion force of the liquid crystal when released to the atmosphere. From this, it can be seen that in the method of manufacturing the liquid crystal display device of the liquid crystal dropping and bonding method, the viscosity (that is, the strength) of the sealing material is very much related to the quality of the manufactured liquid crystal display device.

  In order to prevent the occurrence of the above-mentioned seal pass, it has been conventionally known that a sealing material having a viscosity of 50 Pa · s or more at 25 ° C. is used in a method of manufacturing a liquid crystal display device of a liquid crystal dropping and bonding method (for example, patents). Reference 2). In addition, it is known to use a photo-curing material in order to prevent the occurrence of the above-mentioned sealing path during the curing process of the sealing material (see, for example, Patent Document 3).

JP 63-179323 A (pages 2 and 3, FIG. 1) JP-A-8-106101 (5th page, FIG. 1) JP 2002-122872 A (pages 6-7)

  However, in the conventional manufacturing method using a sealing material having a high viscosity, it is very difficult to pattern the sealing material into a desired shape. Further, in a conventional manufacturing method in which a sealing material is configured using a photocurable material, elements that constitute a liquid crystal display device, such as a liquid crystal and an alignment film, when light is irradiated for curing the sealing material The light may be exposed to the light and adversely affect those elements. For example, the alignment film may be damaged when it receives ultraviolet light.

  The present invention has been made in view of the above-described problems, and in the method for manufacturing a liquid crystal display device of a liquid crystal dropping and bonding method, by curing the sealing material only by heating without using light, It is an object of the present invention to avoid the problem of light-sensitive elements among the components of a liquid crystal display device and to manufacture a high-quality liquid crystal display device.

  A method for manufacturing a liquid crystal display device according to the present invention is a method for manufacturing a liquid crystal display device in which a liquid crystal is sandwiched through a closed annular sealing material, and the sealing material is formed on at least one of the pair of substrates. And a step of dropping liquid crystal on at least one of the pair of substrates, and a step of bonding the pair of substrates, and the bottom point in the time-viscosity curve of the material constituting the sealing material is The viscosity is a viscosity value that does not cause a seal pass between the liquid crystal and the sealing material when the sealing material is thermally cured.

  Further, another method for manufacturing a liquid crystal display device according to the present invention is a method for manufacturing a liquid crystal display device in which liquid crystal is sandwiched through a closed annular sealing material, and the method is provided on at least one of the pair of substrates. In a method for manufacturing a liquid crystal display device, the method comprising: forming a sealing material; dropping a liquid crystal onto at least one of the pair of substrates; and bonding the pair of substrates. The bottom point in the time-viscosity curve is a viscosity value that does not cause misalignment between the pair of substrates when the sealing material is thermally cured.

  Here, the substrate on which the liquid crystal is dropped may be any one of the pair of substrates, or both of the pair of substrates. The above-mentioned “vacuum” includes not only a complete vacuum but also a reduced pressure state close to a vacuum.

Next, the seal path, the misalignment, and the bottom point will be described.
In a method for manufacturing a liquid crystal display device using a liquid crystal dropping and bonding method, a substrate on which liquid crystal is dropped and a substrate on which a sealing material is formed are bonded to each other. Note that the substrate on which the liquid crystal is dropped and the substrate on which the sealing material is formed may be the same or different. Next, the panel structure formed in this manner is pressurized by atmospheric pressure or the like and securely bonded. Next, the sealing material is cured by heating or the like to complete the liquid crystal panel.

  In the above-described series of steps, when the sealing material is cured by heating or the like, the viscosity of the sealing material may decrease and the liquid crystal may enter the inside of the sealing material. This phenomenon is a seal pass. In addition, when the pair of substrates is bonded and the sealing material is cured by heating or the like, when the viscosity of the sealing material decreases, the relative positional relationship between the bonded pair of substrates may shift. This phenomenon is misalignment.

  FIG. 4A shows the change in the viscosity of the sealing material over time when a pair of substrates is bonded to each other and the sealing material bonded to the substrates is raised to a temperature at which it can be cured. It shows a state. In FIG. 4A, time is taken on the horizontal axis and viscosity is taken on the vertical axis.

As shown in the figure, the initial viscosity of 100% is once softened with the lapse of time, and then the curing is started and finally cured to a predetermined hardness according to the material. When the viscosity is once softened, the point at which the viscosity becomes the smallest at time t0 comes. This point P _B is the bottom point.

When the elements of the curve shown in FIG. 4 (a) are analyzed, the curve shown in FIG. 4 (a) shows that a component that decreases the viscosity of the material due to temperature rise and a curing component as shown in FIG. 4 (b). It is combined with an increasing component of strength (that is, viscosity) due to. It can be seen that in this addition, the bottom point P _B is the place where the lowest intensity is obtained between the temperature to be raised and the time axis.

  When the overall strength of the sealing material falls below the expansion force of the liquid crystal at the bottom point, the above-described sealing path is generated. Further, when the fluidity of the sealing material increases as the viscosity of the sealing material decreases, the above-described misalignment occurs. In order to prevent the phenomenon of these seal passes and misalignment, when the bottom point arrives at the time-viscosity curve in the curing process of the seal material, the viscosity corresponding to the bottom point does not cause seal pass or misalignment. It is important that the size.

  As in the present invention, the bottom point in the time-viscosity curve of the material constituting the panel part seal is as follows: (1) When the panel part seal is thermally cured, no seal path is generated between the liquid crystal and the panel part seal. If the viscosity value is set, or (2) the viscosity value is set so as not to cause misalignment between the pair of substrates when the panel seal is thermally cured, a liquid crystal display device of a liquid crystal dropping and bonding method is used. In the manufacturing method of the above, even when the sealing material to which the pair of substrates are bonded is cured, even if the curing is performed only by thermal curing without using light, the liquid crystal display does not generate a seal pass or misalignment. The device can be manufactured.

  In the case where the sealing material is cured using light, there is a possibility that an element that is a constituent element of the liquid crystal display device and has a weak property against light, for example, an alignment film, a liquid crystal, or the like may be adversely affected. On the other hand, if the sealing material can be cured only by heating without using light, such an adverse effect does not occur, so that a high-quality liquid crystal display device can be stably manufactured.

  Next, in the method for manufacturing a liquid crystal display device according to the present invention, the step of forming the sealing material includes a step of forming at least one panel portion seal and a step of forming an outer peripheral seal surrounding the panel portion seal. And in the step of dropping the liquid crystal, it is preferable to drop the liquid crystal in a region surrounded by the panel portion seal.

  Here, the panel portion seal is a seal that contacts the liquid crystal. In general, a plurality of panel part seals are formed on a single large area substrate, a so-called mother substrate. And said outer periphery seal | sticker is formed so that these panel part seal | stickers may be surrounded. Note that “the outer peripheral seal surrounds the plurality of panel portion seals” means a state in which a pair of substrates are bonded together. Therefore, when forming the panel portion seal and the outer periphery seal, both may be formed on the same substrate, or both may be formed on separate substrates.

In addition, “dropping liquid crystal in the area surrounded by the panel part seal”
(1) In the case where liquid crystal is dropped on a substrate on which a seal is formed, the liquid crystal is dropped on a region surrounded by the seal,
(2) When the liquid crystal is dropped onto the substrate on which the seal is not formed, the liquid crystal is dropped onto a region that is surrounded by the seal when the substrates are bonded to form a liquid crystal panel.

  Next, in the method for manufacturing a liquid crystal display device according to the present invention, it is desirable that the material of the sealing material is a thermosetting resin as a main material, and a curing initiator is mixed therewith. If it carries out like this, the bottom point in the time-viscosity curve of a sealing material can be raised according to the characteristic of a hardening start material. In order to increase the bottom point, a method of increasing the viscosity of the material itself may be considered. However, in this case, it may be difficult to pattern the sealing material on the substrate into a desired shape. On the other hand, if the method of raising the bottom point by mixing the curing starting material with the main material is employed, the patterning of the sealing material is easy.

  Next, in the method for manufacturing a liquid crystal display device according to the present invention, the main material is preferably an epoxy compound. The epoxy compound is a compound having an epoxy group in a molecule to be configured. This epoxy compound is excellent in chemical resistance and adhesive strength, and does not require a solvent. These are very convenient in carrying out the manufacturing method of the liquid crystal display device of the liquid crystal dropping and bonding method. In addition, since epoxy compounds are rich in reactivity, a wide range of cured products can be obtained depending on the choice of curing agent and modifying component. Moreover, curing shrinkage during curing is small. Accordingly, the epoxy compound is a very suitable material for curing the sealing material only by thermal curing.

  Next, in the method for manufacturing a liquid crystal display device according to the present invention, it is desirable that a plurality of types of the curing start material are mixed with the main material. If it carries out like this, according to the kind of hardening | curing material, a main material can be hardened in steps. If the main material, that is, the sealing material is cured stepwise, the bottom point can be further increased as compared with the case where the bottom point is increased using one kind of curing material. That is, when the sealing material is cured, the viscosity of the sealing material is maintained high, and the occurrence of a seal pass and misalignment can be reliably prevented.

  Curing materials are roughly classified into aromatic amine compounds, aliphatic amine compounds, amidoamines, polyamides, acid anhydrides, and catalyst curing agents. These curing materials have various characteristics such as the phase state and the temperature contributing to curing. Therefore, a curing material that can contribute to curing in a very wide temperature range can be configured by appropriately combining curing materials having different characteristics. This is very advantageous with respect to raising the bottom point in the time-viscosity curve of the sealant.

  Next, in the method of manufacturing a liquid crystal display device according to the present invention in which a plurality of types of curing initiators are mixed with the main material, the curing initiator has a melting initiator having a melting point higher than 70 ° C. and a melting point of 70 ° C. Or it is desirable that it is two types of hardening starting materials smaller than it. This will be briefly described below.

  The inventor of the present invention has formed a sealing material by mixing one kind of curing initiator with a main material made of an epoxy compound, and manufactured a liquid crystal display device using this sealing material. At that time, a liquid crystal display device was manufactured for each of a curing initiator having a melting point of 60 ° C. and a curing initiator having a melting point of 80 ° C. I confirmed the display of these two types of liquid crystal display devices. As for the liquid crystal display device using the curing initiator having a melting point of 60 ° C., seal pass and misalignment were observed. On the other hand, in the liquid crystal display device using the curing starting material having a melting point of 80 ° C., it has been found that the degree to which the bottom point increases is too large to avoid the seal pass and the assembly displacement. Considering from the results of this experiment, it is desirable that the curing initiator mixed with the main material is a curing initiator having a melting point higher than 70 ° C. and a curing initiator having a melting point of 70 ° C. or lower. It is done.

Next, the curing process in the sealing material will be considered.
Generally, the curing process in the sealing material is roughly divided into (1) curing by radical reaction and (2) curing by chemical change due to structural change such as nucleophilicity. Acrylic compounds are the main materials that cause curing by radical reaction. In addition, an epoxy compound is a main material that is cured by a chemical change. Generally, the curing material is a catalyst that promotes curing by radical reaction and curing by chemical change or a catalyst that initiates the curing.

  The above-mentioned curing material can be (1) one that dissolves by heat, or (2) one that decomposes by heat. “Decomposition” as used herein refers to the decomposition of a compound by heat. The hardened material that is melted by heat is effective when the main material is an epoxy resin. Moreover, the hardener decomposed by heat is effective when the main material is an acrylic resin. About the hardening | curing material decomposed | disassembled by heat, there exists what is called a latent thermosetting agent, and the component which decomposed | disassembled into the acid and the alkali functions as a hardening | curing material decomposed | disassembled by heat. This latent thermosetting agent is described in JP-A-5-295087.

  Examples of the curing material that is dissolved by heat include aliphatic amines, amidoamines, polyamides, aromatic polyamines, acid anhydrides, and catalytic curing agents.

  Further, examples of the curing material that decomposes by heat include peroxides and azo compounds. Peroxides include acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, 2-chlorobenzoyl peroxide, 3-chlorobenzoyl peroxide, 4-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl oxide, 4-bromomethylbenzoyl peroxide, lauroyl peroxide, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid -Tert-butyl, tert-butyl hydroperoxide, tert-butyl performate, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, per-N tert (3- toluic) Karupamin butyl, and the like.

Examples of the azo compound include 2,2′-azobispropane, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo (methylethyl) diacetate, 2,2′- Azobis (2-amidinopropane) hydrochloride, 2,2'-azobis (2-amidinopropane) nitrate, 2,2'-azobisisobutane, 2,2'-azobisisobutyramide, 2,2'-azobis Isobutyronitrile, 2,2′-azobisisobutyronitrile / SnCl ₄ (1 / 21.5), methyl 2,2′-azobis-2-methylpropionate, 2,2′-dichloro-2, 2′-azobisbutane, 2,2′-azobis-2-methylbutyronitrile, dimethyl 2,2′-azobisisobutyrate, dimethyl 2,2′-azobisisobutyrate (SnCl ₄ (1 / 19.53), 1,1 '-Azobi (Sodium 1-methylbutyronitrile-3-sulfonate), 2- (4-methylphenylazo) -2-methylmalonodinitrile, 4,4′-azobis-4-cyanovaleric acid, 3,5-dihydroxy Methylphenylazo-2-methylmalonodinitrile, 2- (4-promophenylazo) -2-allylmalonodinitrile, 2,2′-azobis-2-methylvaleronitrile, 4,4′-azobis-4- Dimethyl cyanovalerate, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobiscyclohexanenitrile, 2,2'-azobis-2-propylbutyronitrile, 1,1'-azobis -1-chlorophenylethane, 1,1′-azobis-1-cyclohexanecarbonitrile, 1,1′-azobis-1-cycloheptanenitrile, 1, '-Azobis-1-phenylethane, 1,1'-azobiscumene, 4-nitrophenylazobenzine ethyl cyanoacetate, phenylazodiphenylmethane, phenylazotriphenylmethane, 4-nitrophenylazotriphenylmethane, 1,1'- Azobis-1,2-diphenylethane, poly (bisphenol A-4,4′-azobis-4-cyanopentanoate), poly (tetraethylene glycol-2,2′-azobisisoptylate), etc. .

(First Embodiment of Manufacturing Method of Liquid Crystal Display Device)
Hereinafter, a method of manufacturing a liquid crystal display device according to the present invention will be described by taking as an example a case of manufacturing a transflective liquid crystal display device using a TFT (Thin Film Transistor) element as a switching element. Of course, the present invention can be applied when manufacturing a liquid crystal display device having any other structure.

  Prior to describing the method of manufacturing a liquid crystal display device according to the present invention, first, a liquid crystal display device manufactured by the method of the present invention will be described. FIG. 5 shows a cross-sectional structure of an example of the liquid crystal display device. FIG. 6 is an enlarged view of a portion indicated by an arrow A in FIG. FIG. 7 shows a planar configuration of the element substrate when the element substrate shown on the upper side in FIG. 6 is viewed from the arrow B direction. FIG. 8A shows a portion indicated by an arrow C in FIG. FIG. 8B shows a cross-sectional structure of the TFT element of FIG. FIG. 9 shows an electrical equivalent circuit of the liquid crystal display device of FIG.

  Note that in each of the above drawings, the mutual dimensional ratio of a plurality of elements constituting the liquid crystal display device is different from the actual dimensional ratio in order to easily show the structure of those elements. Cost.

  In FIG. 5, the liquid crystal display device 1 is formed by mounting a liquid crystal driving IC 3, polarizing plates 4 a and 4 b, and an illumination device 6 on a liquid crystal panel 2. The illuminating device 6 includes an LED (Light Emitting Diode) 7 as a light source and a light guide 8 that guides light generated from the LED 7 to the liquid crystal panel 2. The liquid crystal panel 2 includes a pair of substrates, that is, an element substrate 11a and a color filter substrate 11b, which are bonded together by a sealing material 9 that is rectangular when viewed from the direction of the arrow D. In addition, a square is a square or a rectangle.

  Liquid crystal is sealed in a gap between the element substrate 11a and the color filter substrate 11b and surrounded by the sealing material 9, that is, a so-called cell gap, and the liquid crystal layer 13 is formed. The spacer denoted by reference numeral 15 is formed in a substantially spherical shape, and functions so that the cell gap maintains a uniform dimension. When light is generated from the illumination device 6, the light is modulated for each pixel region by the liquid crystal layer 13, and an image can be displayed on the element substrate 11a side. That is, the observer observes the display from the direction of arrow D.

  The element substrate 11a includes a light-transmitting base material 12a formed of glass, plastic, or the like. The base material 12a is formed in a square shape when viewed from the arrow D direction. A base layer 14 is formed on the surface of the substrate 12a on the liquid crystal side, a TFT element 16 as a switching element and a dot electrode 17 are formed thereon, and an alignment film 18a is formed thereon. The alignment film 18a is subjected to an alignment process for aligning liquid crystal molecules in the liquid crystal layer 13, for example, a rubbing process. The polarizing plate 4a is attached to the outer surface of the substrate 12a by sticking or the like.

  The color filter substrate 11b has a translucent base material 12b formed of glass, plastic or the like. This base material 12b is formed in a square shape when viewed from the direction of the arrow D, similarly to the base material 12a on the element substrate 11a side. A reflective film 19 is formed on the liquid crystal side surface of the substrate 12b, a light shielding film 21 is formed thereon, a coloring element 22 is formed in a region surrounded by the light shielding film 21, and an overcoat is formed thereon. A layer 23 is formed, an electrode 24 is formed thereon, and an alignment film 18b is formed thereon. The alignment film 18b is subjected to an alignment process for aligning liquid crystal molecules in the liquid crystal layer 13, for example, a rubbing process. The polarizing plate 4b is attached to the outer surface of the substrate 12b by sticking or the like.

  The coloring element 22 selectively transmits three primary colors of light, for example, R (red), G (green), B (blue), C (cyan), M (magenta), and Y (yellow). These color elements 22 constitute color filters. When R, G, and B are used as these coloring elements 22, each color coloring element 22 has a predetermined arrangement when viewed from the direction of arrow D in FIG. 5, for example, a stripe arrangement as shown in FIG. They are arranged in a mosaic arrangement as shown in (b) or a delta arrangement as shown in FIG.

  In FIG. 5, the plurality of dot electrodes 17 formed on the base material 12a constituting the element substrate 11a are arranged in a matrix in the vertical direction and the horizontal direction when viewed from the arrow D direction. Each dot electrode 17 is formed in a substantially rectangular shape as shown in FIG. On the other hand, in FIG. 5, the electrode 24 on the side of the color filter substrate 11 b facing the element substrate 11 a is formed as a planar electrode facing all of the plurality of dot electrodes 17. As shown in FIGS. 6 and 7, a region where each dot electrode 17 and the planar common electrode 24 face each other constitutes a display dot region D which is the minimum unit of display. One pixel is formed by the three display dot regions D corresponding to the three coloring elements 22 of R, G, and B. In addition, when performing monochrome display of black and white without using the coloring element 22, one pixel is formed by one display dot region D.

  In FIG. 6, an opening 26 is provided in the reflective film 19 corresponding to each display dot region D. These openings 26 allow the light generated from the illumination device 6 in FIG. 5 to pass as shown by the arrow L1 in FIG. By this transmitted light L1, transmissive display is performed. On the other hand, external light such as sunlight and room light is transmitted through the element substrate 11a as indicated by an arrow L0 and then reflected by the reflective film 19 as follows. A reflective display is performed by the reflected light L0. That is, in the display dot region D, the region where the reflective film 19 is present is the reflective region R, and the region where the opening 26 is present is the transmissive region T.

  In FIG. 7, a plurality of linear gate electrode lines 31 are formed in parallel to each other on the base layer 14 formed on substantially the entire surface of the base material 12a of the element substrate 11a. The energization pattern 32 is formed so as to be connected to each of the gate electrode lines 31. The energization pattern 32 supplies a current to each gate electrode line 31.

The gate electrode line 31 and the dot electrode 17 are connected by the TFT element 16. As shown in FIGS. 8A and 8B, the TFT element 16 includes the following layers on the base layer 14, that is, a gate electrode 33, an anodic oxide film 34 as a gate insulating film, and another gate insulation. A nitride film 36 as a film, an a-Si (amorphous silicon) film 37 as a channel part intrinsic semiconductor film, N ⁺ a-Si (doped amorphous silicon) films 38 and 38 as contact part semiconductor films, and The channel portion protection nitride film 39 is formed by sequentially stacking the layers.

In FIG. 7, a plurality of linear source electrode lines 41 are formed in parallel with each other on the surface of the base material 12 a in a positional relationship orthogonal to the gate electrode lines 31. As shown in FIGS. 8A and 8B, these source electrode lines 41 are stacked on one side of the N ⁺ a-Si film 38 (the left side in FIG. 8B). Further, the dot electrode 17 is laminated on the other side of the N ⁺ a-Si film 38 (that is, the right side in FIG. 8B).

The TFT element 16 having the above configuration is formed as follows, for example. That is, in FIG. 7, first, the base layer 14 is formed by forming Ta ₂ O ₅ with a uniform thickness on the base material 12a by sputtering or the like. Next, Ta (tantalum) is patterned on the base layer 14 by a well-known patterning technique, for example, a photoetching process including a photolithography process and an etching process to form a plurality of linear gate electrode lines 31 and their gates. A gate electrode 33 for the TFT element that protrudes from the electrode line 31 and a conduction pattern 32 that connects the gate electrode lines 31 are formed.

  Thereafter, the base material 12a is immersed in a chemical conversion solution, that is, an anodizing solution, and further, a predetermined voltage is applied to the energization pattern 32 to execute an anodizing treatment, whereby FIG. 8 (a) and FIG. As shown in b), an anodic oxide film 34 is formed on the gate electrode 33 and other patterns.

Next, in FIG. 8B, a gate insulating film 36 is formed on each anodic oxide film 34 by patterning Si ₃ N ₄ by, eg, CVD. Next, a-Si is deposited to a uniform thickness, N ⁺ a-Si is deposited thereon to a uniform thickness, and N ⁺ a-Si is patterned by photo-etching or the like to contact portions. A semiconductor film 38 is formed. Further, the channel part intrinsic semiconductor film 37 is formed by patterning a-Si.

Thereafter, Si ₃ N ₄ is patterned using a well-known patterning technique to form a channel portion protection film 39. Further, a plurality of dot electrodes 17 are formed in a matrix by patterning ITO (Indium Tin Oxide) so as to partially overlap the N ⁺ a-Si film 38 and in a predetermined dot shape. Further, the source electrode line 41 is formed by patterning Al (aluminum) so that a part thereof overlaps with the N ⁺ a-Si film 38 and is arranged in parallel with each other.

  Returning to FIG. 5, the element substrate 11a has an overhanging portion 46 projecting outside the color filter substrate 11b. On the surface of the protruding portion 46, a wiring 47a connected to the gate electrode line 31 on the element substrate 11a in FIG. 7, a wiring 47b connected to the source electrode line 41, and a wiring 47c connected to the common electrode 24 on the color filter substrate 11b. Are formed in an appropriate pattern by a well-known patterning technique, for example, photoetching. Further, an external connection terminal 48 for establishing an electrical connection with an external circuit is formed on the edge of the overhanging portion 46 by the same patterning technique.

  Conductive particles 49 are mixed in a random dispersed state in the sealing material 9 that bonds the element substrate 11a and the color filter substrate 11b together. In FIG. 5, the oval and spherical conductive particles are drawn, but this is a convenient way of drawing for easy understanding of the drawing. Actually, the spherical or cylindrical conductive particles 49 are used as the sealing material. A plurality are included within the width of 9. The electrical connection between the wiring 47c provided on the overhanging portion 46 of the element substrate 11a and the common electrode 24 provided on the color filter substrate 11b is the conductive particles 49 included in the sealing material 9. Is done by.

  Between the external connection terminal 48 and the wirings 47a, 47b, 47c, liquid crystal driving is performed based on COG (Chip On Glass) technology using a conductive bonding material such as ACF (Anisotropic Conductive Film). IC3 is mounted. Of course, any other mounting technology such as TAB (Tape Automated Bonding) technology can also be used.

  The liquid crystal driving IC 3 includes the scanning line driving circuit 51 and the data line driving circuit 52 shown in FIG. 9 for driving the TFT element 16 of FIG. The scanning line driving circuit 51 is connected to the gate electrode line 31 in FIG. 7 and transmits a scanning signal to these lines. On the other hand, the data line driving circuit 52 is connected to the source electrode lines 41 in FIG. 7 and transmits data signals to these lines. The scanning signal is sent to the gate of the TFT element 16, and the data signal is sent to the source of the TFT element 16. When the TFT element 16 is turned on, the corresponding dot electrode 17 is energized and writing to the liquid crystal in the corresponding display dot region D is performed. When the TFT element 16 is subsequently turned off, the written state is maintained. By this series of writing operation and holding operation, the alignment of the liquid crystal is controlled between light transmission and light blocking.

  The liquid crystal display device having the above configuration selects and executes a reflective display using external light such as sunlight or room light and a transmissive display using the illumination device 6 of FIG. 5 as desired. To do. When the reflective display is selected, in FIG. 6, the external light L0 passes through the element substrate 11a and the liquid crystal layer 13, enters the color filter substrate 11b, is reflected by the reflective film 19, and is supplied to the liquid crystal layer 13 again. Is done. On the other hand, when the transmissive display is selected, the LED 7 in FIG. 5 is turned on, and the light from the LED 7 is supplied to the liquid crystal panel 2 by the light guide 8. In FIG. 6, the supplied light L <b> 1 passes through the opening 26 provided for each display dot region D in the reflective film 19 and is supplied to the liquid crystal layer 13.

  As described above, when light is supplied to the liquid crystal layer 13 in each of the reflective display and the transmissive display, the liquid crystal layer 13 has an applied voltage for each display dot region D by the dot electrode 17 and the common electrode 24. And the orientation of the liquid crystal molecules inside is controlled. The light supplied to the liquid crystal layer 13 is modulated by the above-described alignment control, and the modulated light selectively passes through the polarizing plate 4a on the element substrate 11a side in FIG. Images such as numbers, figures, etc. are displayed.

  Hereinafter, an embodiment of a method of manufacturing a liquid crystal display device according to the present invention for manufacturing a liquid crystal display device having the above-described configuration will be described. Of course, the method of the present invention is not limited to this embodiment.

  FIG. 1 is a process diagram showing an embodiment of a method for manufacturing the liquid crystal display device. In this process diagram, processes from process P1 to process P5 are processes for forming the element substrate 11a of FIG. Further, the process from the process P11 to the process P19 is a process of forming the color filter substrate 11b of FIG. The process from the process P21 to the process P27 is a process for bonding the element substrate 11a and the color filter substrate 11b to complete the liquid crystal display device.

  In the present embodiment, one element substrate element is formed on one element substrate mother base to form an element substrate mother substrate, while one color filter substrate mother base is formed. A set of color filter substrate elements is formed thereon to form a color filter substrate mother substrate, and these mother substrates are bonded together to form one liquid crystal display device. That is, the liquid crystal display device is manufactured by a so-called single-chip method.

  Separately from this method, a plurality of sets of element substrate elements are formed on one element substrate mother substrate to form an element substrate mother substrate, and on the other hand, one color filter substrate mother substrate is formed. There is also a method of forming a plurality of sets of color filter substrate elements to form a color filter substrate mother substrate, and bonding the mother substrates together to form a plurality of liquid crystal display devices at the same time, a so-called multi-cavity method. .

  In the following description, the base material having a large area before the element substrate base material 12a of FIG. 5 is obtained by cutting will be referred to as an element substrate mother base material 12a '. A base material having a large area before the color filter substrate base material 12b is obtained by cutting will be referred to as a color filter substrate mother base material 12b '.

  In the process P1 of FIG. 1, the TFT element 16 shown in FIGS. 8A and 8B is formed on the element substrate mother base 12a '. Next, in step P2, the dot electrode 17 shown in FIGS. 8 and 5 is formed. When forming the TFT element 16 and the dot electrode 17, it is desirable to simultaneously form the wirings 47a, 47b, 47c and the external connection terminal 48 of FIG.

  Next, in step P3, the alignment film 18a shown in FIG. 5 is formed. Further, in step P4, the alignment film 18a is rubbed. Next, in step P5, an amount of liquid crystal necessary for forming the liquid crystal layer 13 of FIG. 5 is dropped onto the mother substrate 12a 'using a dispenser or the like. Thus, the elements for the element substrate 11a of FIG. 5 are formed on the mother base material 12a ', and the element substrate mother substrate 11a' is formed.

  While manufacturing the above element substrate mother substrate 11a ′, in step P11, the reflective film 19 of FIG. 5 is formed on the color filter substrate mother substrate 12b ′, and at the same time, the light transmission opening 26 is formed. To do. Next, in the process P12, the light shielding film 21 of FIG. 5 is formed, and in the process P13, the coloring element 22 of FIG. 5 is formed. Thereby, a color filter is formed.

  Next, in step P14, the overcoat layer 23 in FIG. 5 is formed to smooth the surface, and in step P15, the common electrode 24 in FIG. 5 is formed of ITO. Next, in step P16, the alignment film 18b of FIG. 5 is formed, and in step P17, the alignment film 18b is rubbed.

  Next, in step P18, as shown in FIG. 2A, the panel portion seal 9 and the outer peripheral seal 29 are formed on the color filter substrate mother base 12b '. The panel seal 9 is a closed seal and is not provided with an opening for liquid crystal injection. The outer peripheral seal 29 is for forming a vacuum region described later with the panel portion seal 9. The vacuum region is for generating pressure on the substrates by the interaction with the atmospheric pressure after the element substrate mother substrate 11a ′ and the color filter substrate mother substrate 12b ′ are bonded together as described later. belongs to. Therefore, the distance between the panel part seal 9 and the outer peripheral seal 29 is appropriately determined so as to obtain the required pressure.

The panel part seal 9 is the sealing material 9 itself of FIG. The panel part seal 9 is made of a thermosetting resin. The thermosetting resin generally has a time-viscosity characteristic as shown in FIG. Specifically, at the beginning of heating, the viscosity once decreases to the lowest viscosity value, that is, the bottom point P _B , and then the viscosity increases again to be cured to a predetermined viscosity. In the present embodiment, the viscosity of the bottom point P _B is set to a value equal to or higher than a viscosity value that does not cause a seal pass described later and a set displacement described later. Such a setting can be realized, for example, by forming a sealing material with a material obtained by mixing an epoxy compound as a main material and one or more kinds of curing starting materials.

As can be understood by looking at the graph shown in FIG. 4B, the viscosity value at the bottom point P _B of the time-viscosity curve can be increased by mixing the curing initiator with the main material. with proper selection, it can be easily set to a viscosity value not causing Shirupasu and set offset the viscosity value of the bottom point P _B. In addition, the outer periphery seal | sticker 29 can use either a photocurable resin or a thermosetting resin. As the photocurable resin, for example, an acrylic resin can be used.

  Next, in step P19 of FIG. 1, the spacers 15 of FIG. 5 are randomly distributed on the mother base material 12b '. Further, these spacers 15 are fixed on the mother substrate 12b ', that is, on the alignment film 18b. This fixing is performed, for example, by heating the spacer 15. As described above, the elements for the color filter substrate 11b of FIG. 5 are formed on the mother base 12b ', and the color filter substrate mother substrate 11b' is formed.

  After the element substrate mother substrate 11a ′ and the color filter substrate mother substrate 11b ′ of FIG. 5 are formed as described above, in step P21 of FIG. 1, these mother substrates are placed in a vacuum environment, for example, in a vacuum chamber. In FIG. In the conventional manufacturing method in which the bonding operation is performed in the air, the element substrate mother substrate 11a ′ and the color filter substrate mother substrate 11b ′ are individually sucked and held by a vacuum chuck. Those substrates were bonded together.

  However, in this embodiment in which the bonding of the mother substrate is performed in a vacuum environment, the holding using the vacuum chuck cannot be performed because the environment is a vacuum. Therefore, in this embodiment, the bonding operation is performed after the mother substrate is held using the electrostatic chuck. Here, the electrostatic chuck is a chuck method in which a mother substrate is attracted and held using a Coulomb force generated when a voltage is applied to the chuck member. By using this electrostatic chuck, it is possible to perform the bonding operation while supporting the mother substrate even in a vacuum environment.

  When the bonding of the element substrate mother substrate 11a ′ and the color filter substrate mother substrate 11b ′ is completed in the process P21, as shown in FIG. 2B, the element substrate mother substrate 11a ′ and the color filter substrate mother are completed. A panel structure having a structure in which the substrate 11 b ′ is bonded by the panel seal 9 and the outer peripheral seal 29 is formed. Since the liquid crystal has been dropped on the element substrate mother substrate 11a 'in the process P5 of FIG. 1, the liquid crystal layer 13 is formed when the both mother substrates are bonded together. A vacuum region V is formed between the outer peripheral seal 29 and the panel part seal 9.

  Next, in step P22, the panel structure in FIG. 2B is released from the vacuum environment, and in step P23, the panel structure seal 9 and the outer peripheral seal 29 in FIGS. 2A and 2B are removed. The curing process is executed. In this embodiment, since the panel part seal | sticker 9 was formed with the thermosetting resin, the panel part seal | sticker 9 can be hardened only by a heating. The outer peripheral seal 29 may be formed of either a thermosetting resin or a photocurable resin. However, from the viewpoint of not curing by light irradiation, the outer peripheral seal 29 is also formed of a thermosetting resin. It is desirable to keep it.

  By the way, when the panel structure body of FIG. 2B is released to the atmospheric pressure in the process P22, a differential pressure E between the pressure in the vacuum region V and the atmospheric pressure is applied to the outside of the pair of substrates. This force E pressurizes the liquid crystal layer 13 as shown in FIG. 3 (b), and further pressurizes the panel portion seal 9 as shown in FIG. 3 (a). As shown in FIG. 3B, the pressurized liquid crystal layer 13 further pressurizes the panel portion seal 9 in contact therewith. Further, the pressed panel portion seal 9 presses the liquid crystal layer 13 and the vacuum region V, respectively, as shown in FIG.

  As a result of the above pressurization relationship, there is a possibility that liquid crystal erodes the panel portion seal 9 and a seal pass is generated at the interface between the liquid crystal layer 13 and the panel portion seal 9. If this happens, there is a risk that the display characteristics of the liquid crystal display device will deteriorate and the reliability will deteriorate. In addition, at the interface between the panel part seal 9 and the vacuum region V, the panel part seal 9 may continue to expand in the vacuum region V. In this case, there is a possibility that a positional shift, that is, a set shift occurs between the pair of substrates 11a 'and 11b'.

Regarding the above-described seal pass and assembly displacement, if the viscosity of the panel portion seal 9 is high, they can be prevented from occurring. In the present embodiment, in the process P18 of forming the panel portion seal 9 in FIG. 1, the viscosity at the bottom point P _B in the time-viscosity curve in FIG. Set. Therefore, according to the manufacturing method of the present embodiment, the viscosity value at the bottom point of the panel portion seal 9 is maintained at a sufficiently high viscosity value even though the panel portion seal 9 is cured by heating. , Generation of seal pass and misalignment can be completely prevented.

  Temporarily, if the panel part seal | sticker 9 is formed using a photocurable resin, when irradiating it, light irradiation will be performed. In this case, there is no seal pass and misalignment as seen in thermosetting, but on the other hand, light sensitive elements such as alignment films and liquid crystals are adversely affected by light irradiation. There is a risk of receiving. On the other hand, according to the present embodiment in which the panel portion seal 9 is cured only by thermal curing, there is no fear of the above-described adverse effects seen in the case of light irradiation.

  That is, according to the present embodiment, there is no adverse effect on light-sensitive components such as the alignment film, and there is no generation of seal pass and assembly displacement during the thermosetting process, which is extremely reliable. The curing process of the sealing material can be realized.

  After the hardening of the seal is completed as described above, a break process is performed in step P24 of FIG. 1, and the panel structure of FIG. Thereby, the vacuum state of the vacuum region V is released. Moreover, the liquid crystal panel 2 of FIG. 5 is completed by this break. Thereafter, in step P25, the liquid crystal driving IC 3 in FIG. 5 is mounted on the surface of the overhanging portion 46 of the element substrate 11a. In step P26, the polarizing plates 4a and 4b in FIG. By mounting 6, the liquid crystal display device 1 is completed. When attaching the polarizing plates 4a and 4b, other optical elements such as a retardation plate may be attached as necessary.

(Modification)
In the above description, as shown in FIG. 2A, only one liquid crystal display device is formed on the mother substrate 12b ′. That is, the manufacturing method of one piece was implemented. However, a plurality of components of the liquid crystal display device can be formed on the mother substrate 12a ′ on the element substrate side and the mother substrate 12b ′ on the color filter substrate side. That is, it is possible to implement a manufacturing method with a plurality of pieces. In this case, the outer peripheral seal 29 is formed so as to surround the components of the liquid crystal display devices for the plurality of sets. Thereby, when the element substrate mother substrate 11a ′ and the color filter substrate mother substrate 11b ′ are bonded together in the process P21 of FIG. 1, vacuum regions V are formed around the plurality of liquid crystal display device portions.

(Second Embodiment of Manufacturing Method of Liquid Crystal Display Device)
FIG. 11 shows another embodiment of the method for manufacturing a liquid crystal display device according to the present invention. This embodiment differs from the previous embodiment shown in FIG. 1 in the following points. The other points are the same as the embodiment of FIG.

  In the embodiment shown in FIG. 1, the panel portion seal 9 is cured in the process P23 after bonding a pair of substrates. On the other hand, in this embodiment shown in FIG. 11, two types of curing starting materials having different melting points are mixed in the material forming the panel portion seal 9. And in process P20 in the manufacturing process of the color filter substrate performed before bonding a pair of board | substrate together, the panel part seal | sticker 9 is hardened about several to several dozen% at comparatively low temperature. And in process P23 after bonding a pair of substrates together, panel part seal 9 is heated at predetermined temperature, and hardening of panel part seal 9 is completed. If the heating temperature in the first seal curing step P20 and the heating temperature in the second seal curing step P23 are determined according to the characteristics of the curing starting material included in the sealing material constituting the panel portion seal 9, for example, the melting point. good.

As described above, in the present embodiment, the panel portion seal 9 is not cured in a single step, but is cured twice, that is, in a plurality of stages. In some cases, curing can be completed in three or more stages. Thus, if the panel seal 9 so as to cure stages, the viscosity value of the bottom point P _B in viscosity change curve in FIG. 4 (a), the can be further increased as required, which Thus, it is possible to more reliably suppress the occurrence of a seal pass and assembly misalignment.

(Other embodiments)
The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the embodiments, and various modifications can be made within the scope of the invention described in the claims.

  For example, in the above embodiment, the present invention is applied when manufacturing an active matrix type liquid crystal display device using TFT elements as switching elements, but the present invention is a simple matrix that does not use switching elements, that is, a passive matrix type liquid crystal. The present invention can also be applied when manufacturing a display device. The present invention can also be applied to manufacturing an active matrix liquid crystal display device using a two-terminal switching element such as a TFD (Thin Film Diode) element as a switching element.

  The manufacturing method of the liquid crystal display device according to the present invention is suitably used when the liquid crystal display device is manufactured by a liquid crystal dropping and bonding method.

It is process drawing which shows one Embodiment of the manufacturing method of the liquid crystal display device which concerns on this invention. It is a figure which shows the main processes of FIG. 1, Comprising: (a) shows the top view at the time of a seal | sticker formation process, (b) has shown sectional drawing at the time of a bonding process. It is a figure which shows how to apply the applied pressure in the vacuum release process which is the main processes of FIG. (A) is a graph which shows the mode of the change of the viscosity of a sealing material according to progress of time when a sealing material is heated more than hardening temperature. (B) is the graph which analyzed the curve of (a) for every element. It is sectional drawing which shows an example of the liquid crystal display device manufactured by the manufacturing method which concerns on this invention. It is a figure which expands and shows the part shown by the arrow A in FIG. It is a figure at the time of seeing the element substrate in FIG. 6 from the arrow B direction. 8A and 8B are diagrams illustrating a TFT element indicated by an arrow C in FIG. 7, where FIG. 7A is a plan view and FIG. 7B is a side cross-sectional view. It is a figure which shows the electrical equivalent circuit of the liquid crystal display device of FIG. It is a figure which shows the example of an arrangement | sequence of the coloring element in the color filter used with the liquid crystal display device of FIG. It is process drawing which shows other embodiment of the manufacturing method of the liquid crystal display device which concerns on this invention.

Explanation of symbols

1. 1. Liquid crystal display device 2. Liquid crystal panel LCD driving IC, 4a, b. Polarizer,
6). 8. lighting device; Sealing material (panel part seal), 11a. Element substrate,
11a '. Mother substrate for element substrate, 11b. Color filter substrate,
11b '. Mother substrate for color filter substrate, 12a, 12b. Base material,
12a '. Mother substrate for element substrate, 12b ′. Mother substrate for color filter substrate,
13. Liquid crystal layer, 14. 15. Underlayer, Spacers, 16. TFT element,
17. Dot electrodes, 18a, 18b. 18. alignment film, Reflective film, 21. Light shielding film,
22. Coloring elements, 23. Overcoat layer, 24. Electrodes, 26. Opening,
29. Peripheral seal, 31. Gate electrode line, 32. Energization pattern,
33. Gate electrode, 34. Anodized film (gate insulating film),
36. Nitride film (gate insulating film), 37. a-Si film (channel intrinsic semiconductor film),
38. N ⁺ a-Si film (contact part semiconductor film),
39. 41. A nitride film for protecting a channel part (channel part protective film); Source electrode wire,
46. Overhang, 47a, 47b, 47c. Wiring, 48. External connection terminal,
49. Conductive particles; D. Display dot area, L0. Reflected light, L1. Transmitted light,
V. Vacuum region; Reflection region, T.I. Transparent area

Claims (8)

A method of manufacturing a liquid crystal display device in which a liquid crystal is sandwiched through a closed annular sealing material,
Forming the sealing material on at least one of the pair of substrates;
Dropping liquid crystal onto at least one of the pair of substrates;
Bonding the pair of substrates together;
Have
The bottom point in the time-viscosity curve of the material constituting the sealing material is a viscosity value that does not cause a seal pass between the liquid crystal and the sealing material when the sealing material is thermally cured. A method for manufacturing a liquid crystal display device. A method of manufacturing a liquid crystal display device in which a liquid crystal is sandwiched through a closed annular sealing material,
Forming the sealing material on at least one of the pair of substrates;
Dropping liquid crystal onto at least one of the pair of substrates;
Bonding the pair of substrates together;
In a method of manufacturing a liquid crystal display device having
The bottom point in the time-viscosity curve of the material constituting the sealing material is a viscosity value that does not cause misalignment between the pair of substrates when the sealing material is thermally cured. Manufacturing method. In claim 1 or claim 2, the step of forming the sealing material includes a step of forming at least one panel portion seal, and a step of forming an outer peripheral seal surrounding the panel portion seal,
In the step of dripping the liquid crystal, the liquid crystal is dripped in a region surrounded by the panel portion seal.   4. The method for manufacturing a liquid crystal display device according to claim 1, wherein a material of the sealing material is a thermosetting resin as a main material, and a curing initiator is mixed with the sealing material. 5. A method for manufacturing a liquid crystal display device.   5. The method of manufacturing a liquid crystal display device according to claim 4, wherein a plurality of types of the curing start material are mixed with the main material.   6. The method of manufacturing a liquid crystal display device according to claim 5, wherein the curing initiator is of two types: a curing initiator having a melting point higher than 70 ° C. and a curing initiator having a melting point of 70 ° C. or lower. Manufacturing method of liquid crystal display device.   7. The method for manufacturing a liquid crystal display device according to claim 1, wherein the main material is an epoxy compound. 7. The method of manufacturing a liquid crystal display device according to claim 1, wherein the curing initiator is one selected from an aliphatic polyamine, an amidoamine, a polyamide, an aromatic polyamine, or an acid anhydride. A method of manufacturing a liquid crystal display device, wherein

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