JPH10314633A - Coating applicator and production of color filters - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the defects of coating films, such as unequal film thickness distribution and coating distribution, for affecting the functions of thin films by film thickness with a coating applicator for forming thin films, such as color filters. SOLUTION: A compounding tank 16 having a stirrer and viscometer 14 in a circulating route in order to control a coating liquid viscosity having a correlative relation to a constant value is installed as a means for suppressing the coating film thickness distribution. A solvent and coating liquid 17 are compounded while the viscosity is measured therein, by which the coating is executed while the fluctuation in the viscosity of the coating liquid 17 is controlled to ±1 to ±5%. As a result, the waste liquid of the coating layer 17 is eliminated and, therefore, the consumption thereof is reduced. The coating system is a bar coating system. The shape defects of the members for supporting the coating bars are eliminated and the defects of the coating films are decreased by the structure of separating the coating layer contact parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus for applying a coating liquid to a discontinuous substrate such as a glass substrate using a coating bar, and a method for manufacturing a color filter using the apparatus.

[0002]

2. Description of the Related Art In a process of manufacturing a color filter, there is a process of applying a coating liquid composed of a colored photosensitive resin to a thin and uniform thickness on a transparent substrate such as a glass substrate. Conventionally, a spin coater proven in the semiconductor industry has been used for this coating. In this spin coater, a coating liquid is dropped onto the center of rotation while rotating a glass substrate, and the coating liquid is spread and applied by centrifugal force. However, with this spin coater, nearly 90% of the expensive coating solution is scattered, which is a bottleneck in reducing material costs. Japanese Patent Application Laid-Open No. Hei 2-258081 discloses a coating apparatus applying a bar coating method in which a coating liquid is dropped on a coating surface and a coating bar formed of a wire-wound rod is rolled to spread the coating, and a coating apparatus using the coating apparatus. A method has been devised. In this device, the substrate is sandwiched between a pair of upper and lower rollers arranged horizontally, and the lower part of the coating bar, which is the lower roller, is immersed in the coating solution, and the coating bar rotates to apply the surface tension. In this method, an application liquid is pumped up and applied from the lower surface side of the substrate while being measured by a wire on the surface.
In this method, the thickness of the coating surface is determined by the wire diameter of the coating bar and the viscosity of the coating solution.
No. 6, the viscosity of the red, blue and green coating liquids when applied is 3
If it is within ± 30% of the average value of the viscosity at the time of application of the color, it is 0.
It is stated that the thickness can be kept within an allowable range of a film thickness variation of 01 μm. Further, in this method, there is no waste such as scattering of the coating liquid due to rotation unlike a spin coater.

[0003]

However, in the spin coater, the coating liquid can be controlled without contacting with the outside air until immediately before dropping, so that the viscosity is stable without fluctuation.
In the method using this coating bar, although the coating liquid of about 300 cc is circulating, the viscosity fluctuates due to contact with the outside air. In addition, since the solvent is directly supplied to the pan in which the coating liquid is stored in order to suppress the fluctuation, a difference in viscosity occurs in the axial direction of the coating bar. Therefore,
Since the film thickness correlated with the viscosity fluctuates, the apparatus must be stopped for adjusting the viscosity. Further, since the amount of the coating solution in the entire system is constant, there is a waste in that the coating solution is wasted in order to adjust the viscosity. Therefore, the fluctuation of the viscosity causes a decrease in the operation rate and a waste of the coating liquid.

A member supporting the coating bar in the receiving tray is made of a hard synthetic resin in JP-A-5-309304 in view of chemical resistance and reduction of sliding resistance. However, abrasion and scratches occur due to the influence of the shape accuracy of the application bar, and the support member is screwed to the pan so that the shape of the support member may be defective and fine adjustment can be performed, so that the application liquid remains in the gap. In other words, since the particles cannot be removed even by washing, the generation of foreign matter causes poor surface condition of the coated surface.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to an apparatus for applying a coating solution to a substrate by passing the coating solution between a horizontally disposed coating bar and a roller. A mixing tank equipped with a stirrer and a viscometer is provided, and the viscosity signal from the viscometer is taken into the controller, and when the viscosity deviates from the allowable range, a supply signal is sent to the solvent pump or coating liquid pump to return to the allowable range. For example, there is provided a coating apparatus characterized in that fluctuations in viscosity and film thickness are suppressed by sending a stop signal to control the viscosity to ± 1 to 5%.

Further, in the present invention, in the above-mentioned coating apparatus, the coating bar supporting portion of the tray for storing the coating solution and the portion in contact with the coating solution, that is, the coating solution contact portion are integrated by using a polyphenylene sulfide resin. Provided is a coating apparatus that eliminates foreign matter caused by a coating liquid remaining in a gap and reduces unevenness in the shape of a coating bar supporting portion by using the resin.

The present invention also provides a method of manufacturing a color filter by repeating a step of applying a coating liquid comprising a colored photosensitive resin to a transparent substrate and a step of forming a colored pattern by photolithography. The present invention provides a method for producing a color filter, characterized in that the coating liquid is applied while controlling the viscosity of the coating liquid to ± 1% to ± 5% to eliminate residual foreign matter caused by the coating liquid and to reduce line unevenness.

[0008]

FIG. 1 shows a coating apparatus according to the present invention.
As a coating method, a glass substrate 20 is sandwiched between a rotating roll 1 and a coating bar 2 rotating in the opposite direction, and a coating liquid 17 drawn up by a wire (not shown) wound around the surface of the coating bar 2. Is applied to the glass substrate 20 from the lower surface. The application bar 2 is driven by a motor 3 different from the roll 1. First, the problems of the conventional type will be described. FIG. 2 is a schematic view of a conventional chemical preparation.
When the coating liquid 17 is applied to the glass substrate 20, the tray 4
The liquid is supplied from the application liquid tank 10 to the vicinity of the circulation inlet until the liquid level reaches an appropriate level because the liquid amount in the tank is reduced. In addition, a solvent is supplied from the solvent tank 7 to the vicinity of the circulation outlet at regular intervals in order to suppress an increase in viscosity due to volatilization. Therefore, the mixing of the coating liquid 17 and the solvent is performed by the flow generated by the circulation pump 18. The filter 5 is provided on the circulation inlet side of the circulation pump 18 in the circulation path in order to remove dust and foreign matter in the application liquid. However, in this method, since the coating liquid 17 and the solvent and the coating liquid in the receiving pan 4 cannot be reliably mixed, the solid concentration distribution of the coating liquid occurs depending on the location of the receiving pan 4 as shown in FIG. Distribution occurs. In such a case, a waste liquid is required for adjusting the coating liquid, and waste occurs. In addition, A of FIG.
B and C correspond to A, B and C in FIG. 3, respectively. This data is the data when applied to a 300 × 400 glass substrate 20. Since the glass substrate 20 tends to be expanded in the future from the viewpoint of production efficiency, the length of the pan 4 becomes longer and the coating liquid 17 It is expected that the dispensing of the solvent becomes difficult, and the distribution of the film thickness and the amount of waste liquid of the coating liquid increase.

Therefore, according to the present invention, as shown in FIG. 1, the method of mixing in the tray 4 is stopped, and the magnet rotating motor 11, the magnet 12, and the stirrer 1
A mixing tank 16 provided with a stirrer constituted by No. 3 was provided, and a coating liquid and a solvent were supplied thereto to perform mixing. Further, the film thickness is proportional to the solid concentration of the coating solution, but since the solid concentration is correlated with the viscosity, the viscosity and the film thickness are about 0.01 μm for a viscosity change of about 0.1 mPas.
m is related to the change in film thickness. Therefore, a method was adopted in which the viscosity of the coating liquid 17 in the blending tank 16 was kept constant to suppress fluctuations in the film thickness and eliminate waste liquid of the coating liquid. As a method of controlling the viscosity, the viscosity of the coating liquid 17 is measured by the viscometer 14 installed in the mixing tank 16. The measured value is converted by the viscometer controller 15 and the external output is taken into the controller 19. The controller 19 stores therein the reference viscosity of the coating liquid 17 and the upper and lower limit values thereof. For example, as shown in FIG. A command is sent to the supply pump 6 to supply a predetermined amount of solvent from the solvent tank 7. Then, since there is a reaction time until the viscosity changes, if the viscosity at Sm in the sampling time after a certain time T is within the allowable range (upper-lower limit) in FIG. Otherwise, the same operation is repeated until it falls within the allowable range. In an experiment using a color mosaic manufactured by Fuji Hunt, an ultrasonic viscometer F manufactured by Fuji Kogyo was used.
According to UV-1, the upper limit value is 6.4 mPas, and the lower limit value is 6.35.
It has been confirmed that control is possible at mPas, a solvent supply amount of 0.1 cc / time, and T = 10 s. When the application is repeated, the amount of liquid in the receiving pan 4 decreases. Therefore, a command is sent from the controller 19 to the pressure controller 9 based on the measured value of the liquid level gauge 21 to pressurize the application liquid tank 10 and control the liquid supply. The liquid amount is replenished by sending the undiluted coating solution to the blending tank 16 by the container 8. Further, in the present invention, the viscosity is controlled by the blending tank, but the viscosity in the receiving tray 4 actually determines the film thickness. FIG. 5 shows a change in the viscosity of the coating solution in the receiving tray 4. Also in this experiment, a color mosaic manufactured by Fuji Hunt is used, but a low-viscosity type is used. The conditions at the time of viscosity control are an upper limit of 5.16 mPas and a lower limit of 5.1.
Except for 2 mPas, it is the same as the above-mentioned experiment. Even when the viscosity control is performed in the blending tank 16, the viscosity in the receiving pan 4 deviates from the control range of about 5.2 mPas, but fluctuates within the reference value ± 0.1 mPas. However, when the viscosity control is not performed, the viscosity of the coating liquid monotonously increases as shown in FIG.
It can be seen that it deviates from 0.5 mPas corresponding to μm. Therefore, with the above configuration, the viscosity of the coating liquid can be controlled to the reference value ± 0.1 mPas or less, and the waste liquid can be eliminated. The viscosity of the coating solution is about 5 to 10 mP.
Since it is as, it can be said that the viscosity can be controlled to the reference value ± 1 to ± 5%.

Next, the coating bar supporting member in the receiving tray 4 will be described. FIG. 6 is a perspective sectional view showing a conventional structure. The coating bar support member 22 has a semicircular groove formed on the upper surface thereof along the longitudinal direction. The groove supports the coating bar 2 and has a role of preventing bending due to its own weight. The support member 22 is fixed to the tray 4 by a number of screws 24, and the height can be adjusted by the screws 24. However, since the support member 22 is made of synthetic resin, the processing accuracy is poor, and the straightness of the longitudinal ridge line generated by the groove on the upper surface is 0.03 mm or more, or as shown in A in FIG. Protrusion occurs, l is 0.03
When the thickness exceeds mm, the line unevenness 23 tends to occur when applied to the glass substrate 20. FIG. 7 shows a longitudinal sectional view of the coating bar support member 22. Since the coating bar support member 22 is fixed to the tray 4 with the screws 24, a coating liquid residue 25 is generated on the joint surface. Since it cannot be confirmed whether or not it has been removed by washing, it may melt during use and appear as a solid foreign matter 26 when applied to the glass substrate 20.
The line unevenness 23 and the foreign matter 26 cause a defect in the function of the color filter, which causes a reduction in yield. Also,
As the short side of the glass substrate 20 is increased to 500 mm or more, the processing accuracy tends to be worse. Therefore,
In the present invention, as shown in FIG. 8, the liquid receiving part 4 has a liquid tank part 27 in which a coating liquid contact part and a coating bar support part are integrated. As a material of the liquid tank portion 27, polytron sulfide resin FORTRON 0220 (manufactured by Nippler Chemical Co., Ltd.) is employed. The connection between the receiving tray 4 and the liquid tank 27 is similarly fixed by the screw 24, but not all of the joining surfaces are present in the coating liquid. The places where the joint surfaces come into contact with the coating liquid are the holes 28 of the circulation pipe connection holes and the pipe joint mounting holes 29. The joining surface comes into contact with the coating liquid at two points, the entry side and the exit side of the circulation. Although the probability that the coating liquid remains is lower than that of the conventional structure, the coating liquid may enter due to warpage or distortion of the liquid tank 27. Therefore, the outer diameter of the hole 29 is set to be larger than the outer diameter of the hole 28 by 1 to 4 mm. As a feature of the structure of the liquid tank section 27, as shown in FIG. 9, a step h2 on the B side where the substrate comes off is defined by the following equation. The radius of the wire winding portion of the coating bar 2 is R1, the radius of the stepped portion is R2, and the height of the support portion is h.

R1 / 3 ≦ h1 ≦ 2 × R1 / 3 R2-h1 ≦ h2 ≦ h / 2 In the experiment, when R1 = 6.1 mm and R2 = 4 mm, h =
With 12 mm, h1 = 3 mm and h2 = 2, 4, 6 mm, a good surface without defects was obtained. Also, when h2 <1, the coating liquid is accumulated in the portion B on the side from which the substrate comes off, so that the liquid on the side where the substrate enters disappears, and the surface of the coating bar 2 dries, causing defects.

With the above configuration, coating film defects such as stripes and foreign matter can be reduced.

[0013]

According to the present invention, by automatically controlling the viscosity of the coating liquid, it is possible to perform coating with high uniformity of the film thickness, and since the viscosity of the coating liquid is not adjusted by the waste liquid, there is no waste of the coating liquid. Operating rate also increases. Further, since foreign matters and unevenness can be reduced, a high quality color filter can be manufactured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a coating apparatus of the present invention.

FIG. 2 is a schematic view of a conventional applicator tray.

FIG. 3 is an example of a film thickness distribution.

FIG. 4 is a schematic diagram of a viscosity control method.

FIG. 5 is an explanatory diagram of an effect of viscosity control.

FIG. 6 is a perspective sectional view of a conventional saucer.

FIG. 7 is an explanatory diagram of a coupling portion between a coating bar support member and a tray.

FIG. 8 is an explanatory view of a tray structure of the present invention.

FIG. 9 is a cross-sectional view of the saucer application bar support of the present invention.

[Explanation of symbols]

1 ... holding roll, 2 ... coating bar, 3 ... motor,
4 ... pan, 5 ... filter, 6 ... solvent supply pump, 7
... Solvent tank, 8 ... Liquid feed controller, 9 ... Pressure controller,
10: coating liquid tank, 11: stirring drive motor, 12
... magnet, 13 ... stirrer, 14 ... viscometer, 15
... Viscometer controller, 16 ... Mixing tank, 17 ... Coating liquid, 18 ... Circulation pump, 19 ... Controller, 20 ... Glass substrate, 21 ... Level gauge, 22 ... Coating bar support

Claims (3)

[Claims] An apparatus for applying a coating liquid to a substrate by holding a discontinuous substrate horizontally between a coating bar and a pressing member, wherein a stirrer for stirring the coating liquid and a viscosity of the coating liquid are measured. A coating tank having a viscometer for performing the coating, and a controller for controlling the supply amounts of the coating liquid and the solvent using the signal of the viscometer as an input signal. 2. The coating apparatus according to claim 1, wherein a polyphenylene sulfide-based resin is used for a tray supporting the coating bar and storing the coating liquid, and a portion in contact with the coating liquid is integrated to reduce residual foreign matter. A coating device characterized by the above-mentioned. 3. A color filter manufacturing method for manufacturing a color filter by repeating a step of applying a coating liquid comprising a colored photosensitive resin to a transparent substrate and a step of forming a colored pattern by photolithography, A method for producing a color filter, wherein the viscosity of a coating solution to be applied is set to ± 1 to ± 5%.