JP2007003977A - Method for manufacturing liquid crystal apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent or suppress a phenomenon such as intrusion of a liquid crystal into a seal during laminating upper and lower substrates and to provide a liquid crystal apparatus having high reliability. <P>SOLUTION: The method for manufacturing a liquid crystal apparatus having a liquid crystal 50 held between a pair of substrates 10, 20 laminated with a sealing material 52 includes: a step of forming the sealing material 52 on at least one substrate 10 of the pair of substrates 10, 20; and a step of laminating the substrates 10, 20 while holding the liquid crystal 50 in between the substrate 10 having the sealing material 52 formed thereon and the other substrate 20 in a reduced pressure atmosphere. The viscosity of the sealing material 52 in the laminating step is controlled to a range of 100 to 300 Pa s. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid crystal device.

In recent years, as a method for manufacturing a liquid crystal device, an ODF (One Drop Fill) method has been widely used (see Patent Document 1). In this sealing-less method, first, a sealing material is drawn on a substrate, and a liquid crystal is arranged on the substrate when the upper and lower substrates are bonded together. Subsequently, the upper and lower substrates on which the liquid crystal is arranged are bonded together in a vacuum, and the atmosphere is released after bonding. With such a process, a liquid crystal device is manufactured in the sealing-less system. However, in this sealing-less method, since the upper and lower substrates on which the liquid crystal is arranged are bonded together in a vacuum and then released to the atmosphere, a seal pass phenomenon may occur. That is, when the bonded upper and lower substrates are opened to the atmosphere, the sealing material cannot withstand the expansion force of the liquid crystal, and the liquid crystal leaks outside the panel. Therefore, in recent years, a sealing material that can withstand the expansion force of liquid crystal when exposed to the atmosphere (for example, a viscosity of 30 ± 10 Pa · s at 25 ° C.) is used as the sealing material used when the upper and lower substrates are bonded together. Yes.
JP-A-9-127528

However, the viscosity of the sealing material may actually cause a seal pass phenomenon, which is insufficient as the viscosity of the sealing material. Further, the viscosity of the sealing material has the following problems in relation to the amount of liquid crystal and the panel internal volume. In other words, if the amount of liquid crystal placed on the substrate exceeds the internal volume of the panel, the liquid crystal may erode inside the seal, deteriorating the adhesion between the sealing material and the substrate, and causing inconvenience in moisture permeability and peeling. It was. On the other hand, if the amount of liquid crystal is less than the volume in the panel, the inside of the panel is in a negative pressure state, and the sealing material may be drawn into the panel, and there is a problem that the sealing material interferes with the display portion.
The present invention has been made to solve the above-described problems, and suppresses or prevents a phenomenon such as erosion of liquid crystal inside the seal when the upper and lower substrates are bonded to each other to manufacture a highly reliable liquid crystal device. An object of the present invention is to provide a method for manufacturing a liquid crystal device.

In order to solve the above problems, a method for manufacturing a liquid crystal device according to the present invention is a method for manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates bonded together with a sealant. Forming a sealant on at least one of the substrates, placing a liquid crystal on at least one of the pair of substrates, and bonding the pair of substrates. The sealing material is formed with a viscosity lower than the viscosity of the sealing material in the bonding step, and then the viscosity of the sealing material is increased to a viscosity required in the bonding step by a process of increasing the viscosity of the sealing material. It is characterized by being enhanced. Here, as the process, any of a process of heating the sealing material, a process of irradiating the sealing material with ultraviolet light, or a process of leaving the sealing material for a certain period of time can be used.
According to this method, since the viscosity of the sealing material is adjusted to a high viscosity when the upper and lower substrates are bonded together, a seal pass phenomenon that occurs when the viscosity of the sealing material is low can be prevented. This also causes a phenomenon that the liquid crystal generated when the amount of liquid crystal exceeds the volume inside the panel erodes inside the seal, or a phenomenon where the sealing material that occurs when the amount of liquid crystal is less than the volume inside the panel is drawn into the panel. Can be avoided. Further, as compared with the case of using a sealing material having a high viscosity from the beginning, the drawing of the sealing material can be performed smoothly, and the gap material can be easily mixed into the sealing material.

In the present invention, the viscosity of the sealing material in the bonding step is preferably in the range of 100 Pa · s to 300 Pa · s.
According to this method, the seal pass phenomenon can be reliably prevented.

The method for manufacturing a liquid crystal device according to the present invention is a method for manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates bonded together with a sealing material, and at least one of the pair of substrates. A step of forming a sealing material thereon, a step of arranging liquid crystal on at least one of the pair of substrates, and a step of bonding the pair of substrates, The viscosity of the sealing material in the bonding step is controlled in a range of 100 Pa · s to 300 Pa · s.
According to this method, when the upper and lower substrates are bonded together, the viscosity of the sealing material is as high as 100 Pa · s to 300 Pa · s, so that the seal pass phenomenon that occurs when the viscosity of the sealing material is low is ensured. Can be prevented.

In the present invention, after the sealing material is formed at a viscosity lower than the viscosity of the sealing material in the bonding step, the viscosity is required in the bonding step by a process of increasing the viscosity of the sealing material. The viscosity can be increased to a certain viscosity. Here, as the process, any of a process of heating the sealing material, a process of irradiating the sealing material with ultraviolet light, or a process of leaving the sealing material for a certain period of time can be used.
According to this method, as compared with the case of using a sealing material having a high viscosity from the beginning, the drawing of the sealing material can be performed smoothly, and mixing of the gap material into the sealing material can be easily performed.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram of a liquid crystal / sealant coating apparatus used in the manufacturing method of the liquid crystal device of the present embodiment, and FIG. 2 is a schematic configuration diagram of a substrate bonding apparatus used in the manufacturing method. 3 to 5 are step diagrams showing the manufacturing process in order, FIG. 6 is a flowchart of the manufacturing process, and FIG. 7 is a conceptual diagram for explaining the action of the sealing material used in this method. In the following drawings, the ratios of dimensions, film thickness, and the like of each component are appropriately changed in order to make each component easy to see. In the following description, the direction along the surface of the substrate is defined as the X direction (for example, the left-right direction in FIG. 7) and the Y direction (for example, the direction perpendicular to the paper surface in FIG. 7), and the direction orthogonal to the XY plane is Z. This will be described as a direction.

  As shown in FIG. 1, the liquid crystal / sealant coating device (material supply unit) 63 holds the substrate and is movable in the X direction, the Y direction, and the θ direction (rotation direction around an axis parallel to the Z axis). A table 65; a droplet discharge head 66 disposed above the table 65 for discharging and dropping a liquid crystal material; and a seal material application portion 67 disposed near the droplet discharge head 66 for applying a seal material. Consists of the subject. The sealing material applied from the sealing material application portion 67 includes a substantially spherical gap control material, and the diameter of the gap control material is formed to be approximately the same as the cell gap of the substrate (diameter approximately 3 μm). Yes. As a means for dropping the liquid crystal material, any apparatus can be used as long as it can control the amount of liquid crystal material to be dropped, such as a precision liquid discharger (measuring type dispenser) in addition to the liquid drop discharge head 66. Good. In addition, the gap control material is formed in a substantially spherical shape, and is not limited to the one contained in the sealing material, but is formed in a fiber shape and contained in the sealing material, or is not contained in the sealing material and protrudes from the substrate in a column shape. Various types such as those made can be used. Further, the substrate supply / removal unit 62 uses a carrier for transporting the substrate between the liquid crystal / sealant coating device 63 and a substrate bonding device 64 described later.

  As shown in FIG. 2, the substrate bonding apparatus (substrate bonding unit) 64 includes a table 68 that holds the substrate and is movable in the X, Y, and θ directions, and a lower chuck installed on the table 68. Part 69, vacuum chamber 70 disposed above lower chuck part 69, upper chuck part 71 disposed in vacuum chamber 70 so as to face lower chuck part 69, and upper chuck part 71 movable in the Z direction. A lowering mechanism 72 that supports and pressurizes the lower chuck portion 69 toward the lower chuck portion 69. The vacuum chamber 70 is provided with a viewing window 70 a and an exhaust part 76. A bonding microscope 74 for magnifying and observing the alignment mark on the substrate through the sighting window 70a is disposed above the sighting window 70a. The bonding microscope 74 captures an image of the enlarged alignment mark. A CCD camera 81 is provided. The exhaust unit 76 is connected to a suction device 78 such as a vacuum pump for exhausting (evacuating) the gas in the accommodation space 70b. Further, the vacuum chamber 70 is provided with a UV irradiation unit 82 using a fiber or the like as a path from a UV lamp such as a mercury lamp that irradiates ultraviolet rays for temporarily curing the sealing material 52. The UV irradiation unit 82 only needs to supply energy that increases the viscosity of the sealing material 52. The means for applying energy to the sealing material 52 is not limited to the UV lamp, and various devices such as a heating / cooling device and a visible light irradiation device can be used depending on the properties of the sealing material 52.

  Further, the substrate bonding apparatus 64 includes an image processing unit 83 that processes an image captured by the CCD camera 81, and a control that controls the table 68 and the lowering mechanism 72 based on the data processed by the image processing unit 83. A portion 84 is provided. Further, the lower chuck portion 69 and the upper chuck portion 71 are provided with holding mechanisms (not shown) for holding the substrate by holding surfaces 69a and 71a facing each other. The lower chuck portion 69 and the upper chuck portion 71 are mechanisms that can hold the substrate even in a substantially vacuum atmosphere, such as a chuck mechanism using electrostatic force or adhesive force, or a mechanical holding mechanism that mechanically holds the substrate. Any mechanism may be provided as long as it is present. For example, when quartz glass is used for the substrate, if a holding method using electrostatic force is used, the holding force is weak and the relative position of the substrate cannot be adjusted with sufficient accuracy. On the other hand, a holding method such as an adhesive force, an intermolecular force, a vacuum force, or a mechanical holding method can exert a sufficient holding force even with quartz glass, so that the lower chuck portion 69 and the upper chuck portion 71 can be held. It is suitable for use in a mechanism.

Subsequently, a procedure for manufacturing an active matrix liquid crystal device 100 using a thin film transistor (hereinafter abbreviated as TFT) as a switching element using the above manufacturing apparatus will be described with reference to FIGS. To do.
First, a TFT is formed on a glass substrate, and further a pixel electrode and an alignment film are formed to produce a TFT array substrate (step S1 in FIG. 6), while a light shielding film, a counter electrode, an alignment film are formed on the glass substrate. Etc. are formed to produce a counter substrate (step S2 in FIG. 6).
In the following description, the TFT array substrate is referred to as the lower substrate 10 and the counter substrate is referred to as the upper substrate 20.

As shown in FIG. 3A, the upper substrate 20 on which the counter electrode and the like are formed is transported by the substrate feeding / removal unit and supplied to the upper chuck portion 71 of the substrate bonding apparatus 64, and the upper substrate 20 by the holding mechanism. Is retained. On the other hand, the lower substrate 10 on which TFTs and the like are formed is transported by the substrate feeding / unloading unit and fed onto the table 65 of the liquid crystal / sealant coating device 63 (see FIG. 1). Then, while moving the table 65, the sealing material is applied in a closed frame shape from the sealing material application part 67 onto the lower substrate 10 (step S3 in FIG. 6). In the present embodiment, a sealing material having a higher viscosity than that conventionally used here is used. Specifically, a UV curable resin, a thermosetting resin, or the like in the range of 100 Pa · s to 300 Pa · s is used.
Next, the liquid crystal 50 is discharged and dropped from the droplet discharge head 66 while moving the table 65, and the liquid crystal 50 is placed at a position surrounded by the sealing material 52 on the lower substrate 10 as shown in FIG. Arrange (step S4 in FIG. 6). The lower substrate 10 is provided with a spacer 52a for keeping the cell thickness constant. In FIG. 3B, the liquid crystal 50 is shown to be dropped at one place in the region surrounded by the sealing material 52, but the liquid crystal 50 is not limited to being dropped at one place, and is dropped at a plurality of places. It may be dripped.

The lower substrate 10 onto which the liquid crystal has been dropped is transported by the substrate supply / removal unit 62 and supplied to the lower chuck unit 69 as shown in FIG. 3C (in the following description, for convenience, the liquid crystal 50 and the sealing material are used). 52 is omitted) and is held by the holding mechanism.
Then, as shown in FIG. 4A, the vacuum chamber 70 is lowered and brought into contact with the lower chuck portion 69 to close the housing space 70b in a sealed state. When the storage space 70b is in a sealed state, negative pressure is sucked from the exhaust part 76 to bring the inside of the storage space 70b into a substantially vacuum state (1.33 Pa to 1.33 × 10 ⁻² Pa).

  When the inside of the accommodation space 70b is in a substantially vacuum state, as shown in FIG. 4B, an alignment mark (not shown) formed on the upper substrate 20 and the lower substrate 10 is used using a bonding microscope 74. The image is enlarged and taken into the CCD camera 81. The image data of the alignment mark captured by the CCD camera 81 is input to the image processing unit 83, and the relative position between the upper substrate 20 and the lower substrate 10 is detected. Based on the relative position detected by the image processing unit 83, the control unit 84 drives the table 68 to roughly position the relative position between the upper substrate 20 and the lower substrate 10 within an allowable range. Note that the evacuation in the housing space 70b and the rough positioning of the substrates 10 and 20 may be performed concurrently, or the rough positioning may be performed first and the evacuation may be performed later. . When evacuation and rough positioning are performed at the same time, the manufacturing time can be shortened. Further, a through hole 71b is formed in the upper chuck portion 71 at a position directly below the bonding microscope 74 and the viewing window 70a, and the alignment marks of the substrates 10 and 20 are detected through the through hole 71b. be able to.

When the substrates 10 and 20 are roughly positioned, as shown in FIG. 4C, the upper chuck portion 71 is lowered (relatively moved) by the lowering mechanism 72 to bond the opposing substrates 10 and 20 together (in FIG. 6). Step S5). Further, the upper chuck portion 71 is lowered toward the lower chuck portion 69, and pressurizes the substrates 10 and 20 to crush the sealing material 52. When the bonding of the substrates 10 and 20 is completed, the UV irradiation unit 82 irradiates ultraviolet rays to temporarily cure the sealing material 52 and increase the viscosity of the sealing material (step S6 in FIG. 6).
Note that the pressurization after bonding the substrates 10 and 20 may not be performed depending on the manufacturing process and the selection of the sealing material 52 and the like. Similarly, the temporary curing of the sealing material 52 by the UV irradiation unit 82 may not be performed depending on the sealing material 52.
Further, when a deviation is expected between the pasting and the precise positioning, and the amount and direction of the deviation are predicted statistically, the positional relationship between the substrates 10 and 20 after the occurrence of the deviation is described above. Rough positioning may be performed by offsetting in advance so as to be within the range.

  Thereafter, the atmosphere is introduced into the accommodation space 70b, and the pressure is returned from the substantially vacuum state to the atmospheric pressure. When the accommodation space 70b of the vacuum chamber 70 becomes atmospheric pressure, the substrates 10 and 20 are pressed by the pressure difference, and the sealing material 52 is further crushed (step S7 in FIG. 6). Thereafter, as shown in FIG. 5, the holding of the upper chuck portion 71 and the lower chuck portion 69 is released, and the vacuum chamber 70 is raised. Then, the substrate placed in the lower chuck portion 69 in a non-holding state (in this case, the liquid crystal device 100 to which the substrates 10 and 20 are bonded) is removed by the substrate feeding / unloading portion 62. Thereafter, precision alignment and main curing of the sealing material 52 using a UV lamp are performed (step S8 in FIG. 6), and the manufacture of the liquid crystal device 100 is completed.

  In the manufacturing method of the liquid crystal device according to the present embodiment, since the sealing material 52 having a higher viscosity than that conventionally used, for example, about 100 to 300 Pa · s is used, the viscosity of the sealing material is low. It is possible to prevent the seal pass phenomenon occurring in the case. This also causes a phenomenon that the liquid crystal generated when the amount of liquid crystal exceeds the volume inside the panel erodes inside the seal, or a phenomenon where the sealing material that occurs when the amount of liquid crystal is less than the volume inside the panel is drawn into the panel. Can be avoided.

  Here, the present inventors actually made a prototype of a liquid crystal panel using sealing materials with various viscosity values, ease of drawing the sealing material, degree of erosion (seal path) of the sealing material, sealing Evaluation of the ease of crushing of the material was performed. The results are shown in [Table 1]. In the table, “x”, “◯”, and “◎” represent the non-defective product ratio of the liquid crystal panel.

  As apparent from Table 1, when the viscosity of the sealing material 52 is less than 100 Pa, the sealing material is easy to draw and the sealing material is easily crushed, but a sealing pass is likely to be generated and sufficient. Reliability cannot be obtained. On the other hand, when the viscosity of the sealing material 52 is greater than 300 Pa, a sealing pass is less likely to occur, but the ease of drawing the sealing material and the ease of crushing the sealing material are not sufficient. On the other hand, if the viscosity of the sealing material 52 is in the range of 100 Pa · s to 300 Pa · s, good results can be obtained in all of the erosion of the sealing material and the ease of collapsing of the sealing material. Therefore, by using the sealing material in this range, a highly reliable liquid crystal device can be manufactured with a high yield.

[Modification]
FIG. 7 is a flowchart showing another method for manufacturing the liquid crystal device.
The basic steps in this manufacturing method are the same as those shown in FIG. In the previous embodiment, a high-viscosity sealing material was used from the beginning. However, in the manufacturing method of this modified example, a low-viscosity sealing material was first used, and after drawing the sealing material, the high-viscosity sealing material was heated. It is different in that.

  In FIG. 7, the sealing material forming step (step S3) includes a step of drawing the sealing material on the substrate using a low-viscosity sealing material (step S3a), and heating the sealing material to And a step of increasing the viscosity required in the bonding step (step S5) (step 3b).

  In step 3a, a sealing material having the same viscosity as that conventionally used or a lower viscosity is used. Specifically, a UV curable resin, a thermosetting resin, or the like of about 30 Pa · s is used. By using such a low-viscosity sealing material, drawing can be performed smoothly. When the sealing material is drawn in step 3a, processing for increasing the viscosity of the sealing material is performed in step 3b. As this process, any one of a process of heating the sealing material, a process of irradiating the sealing material with ultraviolet rays, or a process of leaving the sealing material for a certain period of time can be used. Table 2 shows the optimum conditions for each treatment. These conditions are conditions for adjusting the viscosity of the sealing material to the above-described range (100 Pa · s to 300 Pa · s).

  In this modification, after the sealing material is first formed with a viscosity lower than the viscosity of the sealing material in the substrate bonding step, the viscosity of the sealing material is required in the substrate bonding step by a process such as heating. It is supposed to be raised to. For this reason, as compared with the case of using a sealing material having a high viscosity from the beginning, the drawing of the sealing material can be performed smoothly, and the gap material can be easily mixed into the sealing material.

[Electronics]
Hereinafter, specific examples of electronic devices including the liquid crystal device of the above embodiment will be described.
FIG. 8 is a perspective view showing an example of a mobile phone.
In FIG. 8, reference numeral 1000 denotes a mobile phone body, and reference numeral 1001 denotes a display unit using the liquid crystal device of the above embodiment.
Since the mobile phone shown in FIG. 8 includes a display portion using the above liquid crystal device, an electronic device having a display portion with excellent display quality can be realized.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, an example of an active matrix liquid crystal device using a TFT as a switching element is given as an example of an electro-optical device. However, an active matrix liquid crystal device using a thin film diode (TFD) as a switching element. A device or a passive matrix liquid crystal device may be used. Furthermore, the present invention can be applied not only to a liquid crystal device but also to other electro-optical devices.

It is a schematic block diagram of the liquid crystal and the sealing material coating device used for the manufacturing method of the liquid crystal device of one Embodiment of this invention. It is a schematic block diagram of the board | substrate bonding apparatus used for a manufacturing method equally. It is process drawing which shows a manufacturing process later on the same. It is a continuation of the process diagram. It is a continuation of the process diagram. 2 is a flowchart of the manufacturing process. It is a flowchart of another manufacturing process. It is a perspective view which shows an example of an electronic device.

Explanation of symbols

10 ... Lower substrate, 20 ... Upper substrate, 50 ... Liquid crystal, 52 ... Sealing material

Claims (6)

A method of manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates bonded via a sealing material,
Forming a sealing material on at least one of the pair of substrates;
Disposing liquid crystal on at least one of the pair of substrates;
Bonding the pair of substrates together,
After the sealing material is formed with a viscosity lower than the viscosity of the sealing material in the bonding step, the viscosity is increased to a viscosity required in the bonding step by a process of increasing the viscosity of the sealing material. A method for manufacturing a liquid crystal device.   2. The liquid crystal device according to claim 1, wherein the process is one of a process of heating the sealing material, a process of irradiating the sealing material with ultraviolet rays, or a process of leaving the sealing material for a certain period of time. Manufacturing method.   The method for manufacturing a liquid crystal device according to claim 1, wherein the viscosity of the sealing material in the bonding step is in a range of 100 Pa · s to 300 Pa · s. A method of manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates bonded via a sealing material,
Forming a sealing material on at least one of the pair of substrates;
Disposing liquid crystal on at least one of the pair of substrates;
Bonding the pair of substrates together,
A method for manufacturing a liquid crystal device, wherein the viscosity of the sealing material in the bonding step is controlled in a range of 100 Pa · s to 300 Pa · s as the viscosity of the sealing material.   After the sealing material is formed with a viscosity lower than the viscosity of the sealing material in the bonding step, the viscosity is increased to a viscosity required in the bonding step by a process of increasing the viscosity of the sealing material. The method of manufacturing a liquid crystal device according to claim 4, wherein:   6. The liquid crystal device according to claim 5, wherein the treatment is one of a treatment of heating the sealing material, a treatment of irradiating the sealing material with ultraviolet rays, or a treatment of leaving the sealing material for a certain period of time. Manufacturing method.

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