CN101101347A - Optical filter and method for manufacturing color filter - Google Patents

Abstract

The invention relates to a method for manufacturing an optical filter. The manufacturing method includes the following steps. First, a substrate is provided, and a black matrix is formed on the substrate, wherein the black matrix has a plurality of openings arranged in an array. Then, a filter material is formed in the opening by ink-jet printing or other methods, and the filter material includes a solvent and a dye mixed with the solvent. Subsequently, a heat treatment is performed, and the volatilization rate of the solvent is slowed down while the heat treatment is performed, so that the filter material is cured. Since the slow volatilization rate of the solvent enables the filter material to still have fluidity during heat treatment, the cured filter material has a flat surface. The filter manufactured by the method has uniform chromaticity and a flat surface.

Description

Optical filter and manufacturing method of color filter

technical field

The present invention relates to a method for manufacturing an optical filter, and in particular relates to a method for manufacturing a color filter capable of improving thickness uniformity.

Background technique

The configuration of the color filter can make the liquid crystal display display in full color. Recently, a method of forming color filters using inkjet printing has been developed. In this manufacturing method, a black matrix is firstly formed on a substrate, which has a plurality of openings. Then, an inkjet printing process is performed to inject filter materials (red, green or blue, etc.) into the openings of the black matrix. Then, heat treatment is performed by baking or heating on a hot plate to dry and solidify the filter material.

Ink-jet printing technology can directly coat the filter material on the substrate to make a color filter. The advantage is that the color filter can be produced without using a mask or a stencil. Inkjet printing technology simplifies the production process of color filters, and does not cause related problems due to the need to use other acid-base solutions.

FIG. 1 is a schematic cross-sectional view of a known color filter produced by inkjet printing. Referring to FIG. 1 , a known color filter 100 includes a substrate 110 and a black matrix 120 disposed on the substrate 110 . Wherein, the black matrix 120 has a plurality of openings P, and the openings P are filled with a filter material 130 . It should be noted that the filter material 130 is filled into the opening P by means of ink-jet printing.

When filling the filter material 130, the liquid level after inkjet printing before the ink is dry often exceeds the height of the black matrix, which may easily cause the filter material 130 to overflow and cross-contaminate. Therefore, the black matrix 120 is often treated with hydrophobic treatment (hydrophobic treatment), in order to increase the surface tension of the filter material 130 on the black matrix 120 to prevent the filter material 130 from cross-contamination. However, as shown in FIG. 1 , under the effect of surface tension, the dried filter material 130 will have a central protrusion and surrounding depressions with poor thickness uniformity. When the color filter 100 has an uneven surface, the step coverage (step coverage) of other film layers formed in the subsequent manufacturing process is relatively poor, so it is necessary to add another layer of flat layer (over coat) to the black matrix 120 and filter material 130, so that the subsequently formed film layer can have better step coverage. In addition, when the color filter 100 is applied to a liquid crystal display, the non-uniform film thickness of the filter material 130 may easily lead to uneven chromaticity (mura) of the displayed image. Therefore, the thickness uniformity of the filter material 130 after drying has always been an important part in the manufacturing process of the color filter 100 .

Contents of the invention

The invention provides a method for manufacturing an optical filter to solve the problem of poor film thickness uniformity of the filter material in the color filter.

The invention provides a method for manufacturing an optical filter. This method includes the following steps. Firstly, a substrate is provided, and a black matrix is formed on the substrate, wherein the black matrix has a plurality of openings arranged in an array. Next, a filter material is formed in the opening, the filter material includes a solvent and a dye mixed with the solvent. Subsequently, a heat treatment is performed, and the volatilization rate of the solvent is slowed down during the heat treatment, so that the filter material is cured.

In an embodiment of the present invention, the aforementioned heat treatment is, for example, pre-baking the filter material to shape the filter material, and then post-baking the filter material to cure the filter material. Wherein, the pre-baking is, for example, carried out in an environment higher than normal pressure (such as 1-5 atm). In addition, the post-baking can be performed under normal pressure environment, higher than normal pressure environment or lower than normal pressure environment. Meanwhile, the pre-baking process temperature is, for example, between 80° C. and 120° C., preferably 90° C. The post-baking process temperature is, for example, between 190°C and 250°C, and preferably 230°C.

In an embodiment of the present invention, the above-mentioned pre-baking is carried out in a cavity, and the gas introduced into the cavity includes a gaseous composition of a solvent, or includes a non-reactive gas that does not interact with the filter material Reactive gas. For example, the gas introduced into the cavity includes air, nitrogen, inert gas and combinations thereof.

In an embodiment of the present invention, the solvent includes propylene glycol monomethyl ether acetate (PGMEA).

In an embodiment of the invention, the method for forming the filter material includes inkjet printing.

In an embodiment of the present invention, after the black matrix is formed on the substrate, it further includes performing a hydrophobic treatment on the black matrix, wherein the hydrophobic treatment includes a plasma process.

In an embodiment of the present invention, the above-mentioned filter material has a flat surface after curing.

A method for manufacturing a color filter, comprising the following steps. First, a substrate is provided. Next, a black matrix is formed on the substrate, wherein the black matrix has a plurality of first group openings, second group openings and third group openings arranged in an array. Then, the first filter material, the second filter material and the third filter material are respectively formed in the first group of openings, the second group of openings and the third group of openings, and the first filter material, the second filter material , The third filter material includes solvent and dye. Afterwards, heat treatment is performed, and the volatilization rate of the solvent is slowed down during the heat treatment, so that the first, second and third filter materials are cured.

In an embodiment of the present invention, the above-mentioned first, second and third filter materials include blue, green and red filter materials.

In an embodiment of the present invention, the above-mentioned heat treatment is carried out under an environment higher than normal pressure.

In an embodiment of the present invention, the above-mentioned first, second and third filter materials have flat surfaces after curing.

Because the present invention slows down the volatilization rate of the solvent in the filter material by an environment higher than normal pressure or other means during the pre-baking step so that the filter material is formed, the filter material is still in the process of curing. It has fluidity, so that the cured filter material has a flat surface and uniform film thickness.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a known color filter produced by inkjet printing.

2A to 2D illustrate a manufacturing method of a color filter according to an embodiment of the present invention.

Figure number:

100: color filter

110, 210: Substrate

120, 220: black matrix

130, 230: filter material

200: filter

240: Nozzle

250: pre-baked

P: open

Detailed ways

2A to 2D illustrate a manufacturing method of an optical filter according to an embodiment of the present invention. The manufacturing method of the optical filter of this embodiment includes the following steps. First, referring to FIG. 2A , a substrate 210 is provided, and a black matrix 220 is formed on the substrate 210 . The black matrix 220 has a plurality of openings P, and the openings P are arranged in an array, and the black matrix 220 is, for example, a resin black matrix or a metal black matrix.

After forming the black matrix 220 , for example, a hydrophobic treatment may be performed on the surface of the black matrix 220 to avoid overflow of the filter material in subsequent processes. Generally speaking, the method of hydrophobic treatment is, for example, performing a plasma process to form hydrophobic substances on the surface of the black matrix 220 .

Next, referring to FIG. 2B , a filter material 230 is formed in a plurality of openings P of the black matrix 220 . In this embodiment, the method of forming the filter material 230 includes performing an inkjet printing process to fill the filter material 230 into the opening P through the nozzle 240 . Specifically, the filter material 230 includes a solvent and a dye mixed with the solvent, wherein the solvent is, for example, propylene glycol monomethyl ether ethyl ester (PGMEA) or other similar solvents, and the dye, for example, has red, green or blue color, etc. Dyes of different colors.

Since the surface of the black matrix 220 has undergone hydrophobic treatment, when the filter material 230 fills the opening P, the interface tension between the filter material 230 and the surface of the black matrix 220 is relatively high. Therefore, the filter materials 230 of different colors are not easy to overflow and contaminate each other. At the same time, the black matrix 220 after the hydrophobic treatment tends to make the filter material 230 present an uneven surface with a central protrusion and a depression around it (as shown in FIG. 2B as shown).

Then, a heat treatment step is performed, and the volatilization rate of the solvent is slowed down during the heat treatment step. Please refer to FIG. 2C , the heat treatment step is, for example, pre-baking 250 the filter material 230 to make the filter material 230 shape. It is worth mentioning that the step of pre-baking 250 is, for example, carried out under an environment higher than normal pressure (such as 1-5 atm), and the process temperature of pre-baking 250 is, for example, between 80° C. and 120° C. A preferred process temperature is, for example, about 90°C.

In one embodiment of the present invention, the pre-baking 250 can be carried out in a cavity. In order to increase the pressure in the cavity, this embodiment can adopt the method of feeding gas to make the pressure in the cavity higher than normal. pressure. The gas introduced into the chamber can be a gaseous component of a solvent, or include a non-reactive gas, which is a gas that does not react with the filter material 230 . In detail, according to this embodiment, for example, propylene glycol monomethyl ether ethyl ester gas, air, nitrogen gas, or inert gas can be passed into the cavity. The present invention can pass through the gas that does not react with the filter material 230 to increase the total pressure of the gas in the cavity (total pressure), and also can pass through the gaseous composition of the solvent to increase the gas partial pressure of the solvent in the cavity pressure), which can also slow down the volatilization rate of the solvent.

When pre-baking 250 is carried out in a cavity with gas, the pressure applied by the gas to the filter material 230 will slow down the volatilization rate of the solvent, and the greater the pressure applied by the gas, the faster the volatilization rate of the solvent. slow. Specifically, before the filter material 230 is fully formed, the volatilization rate of the solvent is relatively slow (compared with normal pressure), so that the filter material 230 can maintain fluidity. Therefore, after the filter material 230 is formed, a relatively flat surface, a relatively uniform film thickness (as shown in FIG. 2C ) and a flat surface can be obtained.

In addition, the heat treatment step also includes post-baking (not shown) the filter material 230 after the pre-baking 250 to completely dry and cure the filter material 230 to form the filter 200 . Since the shape of the filter material 230 has been fixed during the pre-baking step 250 , the appearance and flatness of the filter material 230 will not be affected no matter what pressure the post-baking step is performed on. Therefore, the post-bake can be performed under normal pressure, higher than normal pressure or lower than normal pressure. In addition, the process temperature of the post-baking (not shown) is, for example, between 190° C. and 250° C., preferably about 230° C., so as to volatilize the solvent and form the optical filter 200 (as shown in FIG. 2D ).

In addition, in other embodiments, the above method can be applied to fabricate color filters. Wherein, the openings P of the black matrix 220 may be a first group of openings, a second group of openings and a third group of openings arranged in an array. When the openings P of the black matrix 220 can be the first group of openings, the second group of openings and the third group of openings arranged in an array, the first filter material, the second filter material, and the third filter material can be formed in each opening correspondingly. filter material. The first filter material, the second filter material and the third filter material may be blue, green and red filter materials. Moreover, the heat treatment step when curing the first, second and third filter materials is, for example, carried out in an environment higher than normal pressure (such as 1-5 atm), so that the first, second and third filter materials The material has a flat surface after curing.

Generally speaking, when the filter 200 is formed by inkjet printing, the selection of the solvent in the filter material 230 is often an important issue. For example, if a material with a lower boiling point is selected as the solvent, the solvent volatilizes faster, so the temperature required for drying the filter material 230 is lower and the process time is shorter. However, if a large-scale color filter is to be manufactured, the steps of filling the filter material 230 must be performed multiple times, and the filter material 230 filled into the opening P earlier may be partially dried before the heat treatment step, and Causes the manufacturing process to be difficult to control. In order to improve the above problems, multiple multi-head nozzles can be used at the same time to shorten the time for filling the filter material 230 . However, using multiple multi-head nozzles at the same time increases the cost of process equipment.

If a material with a higher boiling point is used as the solvent, the solvent volatilizes at a slower rate, but the problem of uneven drying is less likely to occur. Therefore, it is not necessary to use more expensive multi-head nozzles to save equipment costs. In particular, according to the proposed embodiment of the present invention, the slower evaporation rate of the solvent helps to make the optical filter 200 have a flatter surface. In contrast, in order to manufacture the filter 200 with a flat surface, the solvent of the filter material 230 is preferably a material with a higher boiling point. For example, ethyl propylene glycol monomethyl ether has a boiling point of about 145° C. to 146° C., which is a solvent with a relatively high boiling point, and it can be used as the solvent selected in this embodiment.

In summary, during the manufacturing process of the color filter of the present invention, when the filter material is formed, the volatilization rate of the solvent is slowed down by the influence of pressure, so that the dried filter material has a flat surface and a uniform film thickness. . Therefore, when the color filter is applied to a liquid crystal display, uneven chromaticity will not occur. In addition, the flatness of the color filter produced by the manufacturing method of the present invention is good, and there is no need to cover the flat layer for subsequent film layer manufacturing, so the manufacturing cost can be reduced and the manufacturing process can be simplified.

Although the present invention has been disclosed with specific embodiments, it is not intended to limit the present invention. Any person skilled in the art can make replacements of equivalent components without departing from the concept and scope of the present invention, or replace them according to the present invention. The equivalent changes and modifications made in the scope of patent protection shall still fall within the scope of this patent.

Claims (23)

1. the manufacture method of an optical filter, this method comprises:

One substrate is provided;

Form a black matrix on this substrate, wherein should deceive the opening that matrix has a plurality of arrayed;

Form a filter in described opening, this filter comprises a solvent and a dyestuff;

Carry out a thermal treatment, and slow down this thermal treatment when carrying out, the rate of volatilization of this solvent is so that this filter solidifies.

2. the manufacture method of optical filter as claimed in claim 1 is characterized in that: carry out this thermal treatment and comprise:

This filter is carried out a prebake conditions, so that this filter is shaped;

This filter is carried out a back baking, so that this filter solidifies.

3. the manufacture method of optical filter as claimed in claim 2 is characterized in that: this prebake conditions is to carry out being higher than under the environment of normal pressure.

4. the manufacture method of optical filter as claimed in claim 3 is characterized in that: this back baking is to carry out under the environment of normal pressure.

5. the manufacture method of optical filter as claimed in claim 3 is characterized in that: this back baking is to carry out being higher than under the environment of normal pressure.

6. the manufacture method of optical filter as claimed in claim 3 is characterized in that: this back baking is to carry out being lower than under the environment of normal pressure.

7. the manufacture method of optical filter as claimed in claim 2, it is characterized in that: the technological temperature of this prebake conditions is between 80 ℃ to 120 ℃.

8. the manufacture method of optical filter as claimed in claim 2, it is characterized in that: the technological temperature of this prebake conditions is 90 ℃.

9. the manufacture method of optical filter as claimed in claim 2 is characterized in that: the technological temperature of this back baking is between 190 ℃ to 250 ℃.

10. the manufacture method of optical filter as claimed in claim 2 is characterized in that: the technological temperature of this back baking is 230 ℃.

11. the manufacture method of optical filter as claimed in claim 2 is characterized in that: this prebake conditions is to carry out in a cavity.

12. the manufacture method of optical filter as claimed in claim 11 is characterized in that: feed the gaseous state constituent that the interior gas of this cavity comprises this solvent.

13. the manufacture method of optical filter as claimed in claim 11 is characterized in that: the gas that feeds in this cavity comprises a nonreactive gas, for not with the gas of this filter reaction.

14. the manufacture method of optical filter as claimed in claim 11 is characterized in that: the gas that feeds in this cavity comprises air, nitrogen, inert gas and combination thereof.

15. the manufacture method of optical filter as claimed in claim 1 is characterized in that: this solvent comprises the propylene glycol monomethyl ether ethyl ester.

16. the manufacture method of optical filter as claimed in claim 1 is characterized in that: the method that forms this filter comprises ink jet printing.

17. the manufacture method of optical filter as claimed in claim 1 is characterized in that: form should black matrix on this substrate after, more comprise this black matrix carried out a hydrophobic treatments.

18. the manufacture method of optical filter as claimed in claim 17 is characterized in that: this hydrophobic treatments comprises plasma process.

19. the manufacture method of optical filter as claimed in claim 1 is characterized in that: this filter has a flat surfaces after solidifying.

20. a manufacturing method of color filters, this method comprises:

One substrate is provided;

Form a black matrix on this substrate, wherein should have one first group of opening of a plurality of arrayed, one second group of opening and one the 3rd group of opening by black matrix;

Form one first filter, one second filter, one the 3rd filter respectively in this first group of opening, this second group of opening and the 3rd group of opening, this first filter, this second filter and the 3rd filter comprise a solvent and a dyestuff;

Carry out a thermal treatment, and slow down this thermal treatment when carrying out, the rate of volatilization of this solvent is so that this first filter, this second filter and the 3rd filter solidify.

21. manufacturing method of color filters as claimed in claim 20 is characterized in that: this first filter, this second filter and the 3rd filter comprise blueness, green and red filter.

22. manufacturing method of color filters as claimed in claim 20 is characterized in that: this thermal treatment is included under the environment that is higher than normal pressure to be carried out.

23. manufacturing method of color filters as claimed in claim 20 is characterized in that: this first filter, this second filter and the 3rd filter have a flat surfaces after solidifying.

Images