JP2000071597A - Printed method of thin film structure and execution apparatus for this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thin film structure through application accurately at a relatively low cost by positioning a printing stereotype having a printing material to a substrate to be printed, and arranging a means for contacting the stereotype with the substrate. SOLUTION: After positioning a substrate 13 taking a stereotype 11 as a reference, the stereotype 11 and substrate 13 are brought into contact with each other. In order to make the substrate 13 mount on the stereotype 11 positively uniformly, high overpressure is applied to a chamber 17 in place of negative pressure in the chamber 17 before contact. After adhering to a soft flexible layer 14 from its recesses 10 filled with color materials 12, the substrate 13 is lifted and removed from the stereotype 11. In addition, for printing other colors such as green and blue, it is most preferable that printing is repeated after the printed layer is subjected to drying treatment and curing treatment. After the completion of printing, the layer structure including the flexible layer 14 is hardened, thereby preferably stabilizing the layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for printing thin-film structures, such as color filters, cover matrices, etc. of liquid crystal displays, on substantially rigid substrates, such as glass substrates, plastic substrates and the like, and to implementing the method. To a device for doing so.

[0002]

2. Description of the Related Art Printing methods for the application of thin films are used, for example, for the formation of color filters in "simple matrix" liquid crystal displays having large pixel structures.

A liquid crystal display is basically composed of two parallel flat substrates (glass substrates), and has a liquid crystal material provided between these two parallel flat substrates and used as a light valve. In contrast to a simple matrix liquid crystal display, in an active matrix liquid crystal display, generally, a rear substrate in a viewing direction supports an active element such as a thin film transistor.
In the case of a display capable of displaying color, a color filter is applied to the front substrate, and this color filter is regularly fitted in a black matrix window in the case of a matrix display. The main purpose of this black matrix is to clearly demarcate optically active surfaces.

[0004] According to today's manufacturing techniques, mosaic color filters are applied in a series of multiple photolithographic processes in an active matrix liquid crystal display. In this case, a black matrix is first formed, and the windows of this black matrix are then fitted with color filters of the three primary colors in three successive process steps. Color filter materials often consist of dyed lacquer. Heretofore, the color filter structure required only in simple matrix displays, which usually consist of relatively rough structures, has been produced by cost-effective printing methods. In this case, offset printing technology is usually used. This type of printing technique is generally no longer applicable for small pixel sized active matrices. This is because the accuracy of this printing technique is limited in terms of edge roughness and minimally achievable structure.
In principle, better resolution is obtained by using an intaglio printing method. The tampon intaglio printing method is generally used for rigid printing surfaces. In this tampon intaglio printing method, the elastic tampon can naturally cause distortion of the transferred image.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for printing a thin-film structure in which the thin-film structure is applied with sufficient accuracy and relatively low cost, as well as an apparatus for implementing the method. That is.

[0006]

The above object is achieved by a method comprising the steps of: a. Applying a material for forming a structure to a printed stereotype with a doctor blade and applying the material in the printed stereotype; On the contrary, the structure to be printed is in a recess, b. Providing a flexible soft covering layer on the substrate to be printed before the printing process, c. After positioning the stereotype accordingly with respect to the substrate in the printing process. This is solved by a method step of bringing this stereotype into contact with the substrate.

Another object of the present invention is to provide a device in which a means for fixing a substrate to be coated is provided, and a printing stereotype having a printing material is positioned with respect to the substrate to be printed. This is solved by the presence of means for making contact with the stereotype.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for printing thin film structures, such as color filters, cover matrices, etc. of liquid crystal displays, on substantially rigid substrates, such as glass substrates, plastic substrates, and the like. The central technical idea of the method of the present invention resides in that the method has the following method steps. A. Apply the material for forming the structure to a printing stereotype, for example a doctor blade, on an etched and / or engraved metal plate. On the contrary, the structure applied in this printing stereotype exists in the concave portion.

B. A method step in which the substrate to be printed is provided with a flexible soft covering layer before the printing process. A soft polyimide layer is preferably used as the covering layer.

C. In the printing process, the stereotype is brought into contact with the substrate after the stereotype has been correspondingly positioned with respect to the substrate, whereby the material filled in the relatively recessed structure is transferred to the surface of the substrate to be printed. The desired structure is formed as a result.

The printing technique produces a structure with high accuracy. This is because unlike the tampon printing method, cushion distortion does not occur during print transfer. This is because transfer is performed directly to the substrate without a flexible tampon. Rather, in the manner of the present invention, the tampon used in other cases is replaced by a flexible soft covering layer that remains on the substrate. But,
This coating has a much smaller deformation in the printing process than the tampon normally used in other cases, so that no unwanted transfer distortions occur.

For the production of a mosaic color filter, for example for an active matrix liquid crystal display, this printing process is simply repeated in three primary colors, red, green and blue, as long as it is operated by an additive color filter. During each printing phase only a short drying step of the color lacquer that has just been applied is required.

After the end of the printing process, it is advantageous if the applied color lacquer, which is soft and flexible, is cured during the printing process, as well as the coating applied before printing. As a result, the stability of the formed layer system is improved.

The curing step is performed, for example, thermally or by UV irradiation.

Typical layer thicknesses produced by the method according to the invention are between 2 μm and 10 μm.

In order to simplify the printing process, it is particularly advantageous if the substrate to be printed is positioned "face-down", ie with the printed side facing down, above the stereotype. .

For the most accurate positioning of the substrate relative to the stereotype, it is proposed that the deflection of the substrate is further prevented by applying a negative pressure to the backside of the substrate.

Furthermore, in order to obtain a uniform printed image, it is proposed to increase the pressure on the back surface of the substrate while the stereotype and the substrate are in contact during the printing process.

The apparatus for carrying out the method according to the invention comprises means for fixing a substrate to be coated and a printing stereotype having a printing material relative to the substrate to be printed, Includes means for contacting the stereotype.

For the simple construction of the device according to the invention, it is proposed that the fixing means for fixing the substrate are provided with the layer side facing down.

In order to support the substrate efficiently, it is proposed that the fixing means have a vacuum channel surrounding the periphery, which vacuum channel holds the substrate in the peripheral region.

Depending on whether the substrate is fixed and positioned "face-down" or "face-up" in this device, the positioning means for bringing the substrate and stereotype into contact may include a negative pressure on the backside of the substrate. Or it is particularly advantageous if it is configured to apply an overpressure. This avoids board flexing that can impair precise adjustment of the board to the stereotype.

That is, the positioning means for bringing the substrate into contact with the stereotype is configured to increase the pressure on the back surface of the substrate during the printing process.

Advantageous embodiments of the invention result from the dependent claims.

[0025]

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described in more detail below with reference to the drawings, together with the advantages of the invention.

FIGS. 2a to 2i show a substrate 1 of a matrix liquid crystal display. The substrate 1 is provided with a mosaic color filter by a conventional photolithography process. The method is divided into the following steps: a. First photosensitive color layer 2 (eg red) on the substrate
Is spin-coated (FIG. 2a).

B. The photosensitive color layer 2 is subsequently exposed by means of a corresponding mask 3 (FIG. 2b).

C. Leave the exposed structure 4 behind in the development process (FIG. 2c) and remove the parts that are not exposed. The remaining structure 4 is then dried.

D. Next, the second photosensitive color layer 5
(Eg green) is spun on (FIG. 2d), exposed by a suitable mask 6 (FIG. 2e), and the exposed structure 7
Are dried after the development step (FIG. 2f) in which is left.

E. The third color layer (eg, blue) is shown in FIG.
g to FIG. 2i, correspondingly applied, structured and dried, finally completing the mosaic color filter, shown in cross section in FIG. 2i.

To avoid the disadvantages of this extremely costly process, color filters can be formed by the method according to the invention according to FIGS. 1a to 1d.

First, a red color material 12 is applied by a doctor blade 13 to a schematically shown stereotype 11 having an opening 10 corresponding to, for example, a color filter structure for red. The direction in which the doctor blade 13 is scraped is indicated by an arrow in FIG. 1a.

The substrate 13 is positioned and adjusted above the stereotype 11 thus filled. A soft flexible thin film 14, for example, a polyimide layer is applied to the back surface of the substrate to be coated. This substrate 13 is held by a suitable vacuum means 15 at the “face-down position”. The vacuum means 15 includes, for example, a vacuum channel 16 surrounding the periphery, so as to hold the substrate at the periphery. Further, the vacuum means 15 is configured such that a chamber 17 is formed by the sucked substrate 13. The pressure in this chamber 17 can be adjusted separately (FIG. 1).
b).

After the positioning of the substrate 13 is adjusted with reference to the stereotype 11, the stereotype 11 is brought into contact with the substrate 13. To ensure that the substrate rests on the stereotype 11 reliably and uniformly, an overpressure is applied to the chamber 17 instead of a negative pressure in the chamber 17 which prevents the substrate from bending downward before contacting.
Substrate 13 is lifted off of stereotype 11 after it has been deposited from color-filled opening or recess 10 into soft flexible layer 14 (FIG. 1).
d).

In order to print further colors, for example green and blue, this printed process just described is carried out after the printed layer has been advantageously treated in a drying or curing step. Simply repeat.

However, the finished layer structure, including the soft flexible layer 14, is preferably further cured after the end of the printing process. This results in improved layer stability.

[Brief description of the drawings]

FIG. 1 shows in cross-section a schematic representation of a stereotype and a substrate held “face down” belonging to this stereotype, illustrating the various process steps in carrying out the manufacturing method of the invention. Is shown.

FIG. 2 illustrates a cross-sectional view of a substrate at various process steps during the application of a color filter and a conventional photolithographic process.

[Explanation of symbols]

 Reference Signs List 1 Substrate 2 Photosensitive color layer 3 Mask 4 Exposed structure 5 Photosensitive color layer 6 Mask 7 Exposed structure 10 Opening 11 Stereotype 12 Color material 13 Substrate 14 Soft flexible thin film 15 Vacuum means 16 Vacuum channel 17 chamber

Claims (9)

[Claims] 1. A method for printing a thin film structure, such as a color filter, a cover matrix, etc. of a liquid crystal display, on a substantially rigid substrate, for example a glass substrate, a plastic substrate, etc., comprising the following method steps: a. The material for forming the structure is applied to the printing stereotype (11) with a doctor blade, and the structure (12) applied to the printing stereotype (11) is present in the recess in reverse, b. The substrate (13) is provided with a flexible soft covering layer (14) prior to the printing process; c. After the stereotype (11) is appropriately positioned with respect to the substrate (13) in the printing process. Method for contacting a stereotype (11) with said substrate (13), color filter for liquid crystal display, cover matrix Substantially rigid substrate, for example a glass substrate, a method for printing such as a plastic substrate a thin film structure, such as. 2. The method according to claim 1, wherein the substrate to be printed is positioned "face down" above the stereotype. 3. Deflection of the substrate (13)
3. The method as claimed in claim 1, wherein the blocking is effected by applying a negative pressure to the back surface of the device. 4. In a printing process, a stereotype (1)
In order to bring the substrate (1) into contact with the substrate (13),
3. The method according to claim 1, wherein the pressure on the back surface is increased.
The method according to one of claims 1 to 3. 5. An apparatus for carrying out the method according to claim 1, wherein the means for fixing a substrate to be coated is provided.
And a printing stereotype (11) having a printing material (12).
2. A device according to claim 1, characterized in that there are means (15) for positioning the substrate (13) with respect to the substrate (13) to be printed and for bringing the substrate (13) into contact with the stereotype (11). An apparatus for performing the method of any one of the preceding claims. 6. The device according to claim 5, wherein the fixing means for fixing the substrate is provided with the layer side facing down. 7. The fixing means has a vacuum channel (16) surrounding the periphery, said vacuum channel (16) being provided on the substrate (1).
7. The device according to claim 5, wherein 3) is held in a peripheral region. 8. A substrate (13) and a stereotype (11).
Positioning means (15) for contacting the substrate (13) with the substrate (13) to prevent deflection of the substrate (13).
8. The device according to claim 5, wherein the device is configured to apply a negative pressure or an overpressure to the back surface of the device. 9. A substrate (13) and a stereotype (11).
9. A method according to claim 5, wherein the positioning means for contacting the substrate are configured to increase the pressure on the back side of the substrate during the printing process. The described device.