Coating method for large glass substrates

Abstract

Provided is a method for coating large area glass substrates, comprising the steps of: a) applying a water-soluble layer to at least one first predetermined area of ​​the surface of the glass substrate, leaving at least one second predetermined area of ​​the surface of the glass substrate free of the water-soluble layer; b) coating the surface of the glass substrate with at least one water-insoluble layer; and c) removing the water-soluble layer, wherein steps a) to c) are performed multiple times in succession.

Description

[Technical field]

[0001] The present disclosure relates to an iterative method for coating large area glass substrates.

[0002] The so-called lift-off methods using photoresist (photolithography) are known in electronics. In these methods, a photoresist is applied to a substrate and, using a mask, is exposed and developed at the positions defined by the mask. The unexposed places of the photoresist are then removed using a corresponding solvent. In a further step, the substrate or the photoresist is coated with a material (alternatively, etching methods can be used to remove the material). As a final step, the photoresist is removed from the substrate using a corresponding solvent, thus also removing the material layer applied to the photoresist. The substrate is thus left with the material layer at the positions where the photoresist was not present during coating.

[0003] Due to the complicated work steps in the known methods (coating with photoresist, exposing, developing), these methods are not suitable for large area coating.

[0004] An alternative masking technique is applied in the automotive industry. A masking layer is applied here by screen printing. In a further step, the masking layer is dried in an oven before the sputtering process and then a low-e layer is applied. After coating, the masking layer is dissolved for a certain time and then washed away together with the overlying layer.

[0005] It is an object of the present disclosure to provide a method that allows for efficient coating, especially of large area glass substrates, compared to known methods.

[0006] This object is achieved by means of the features of the independent claims. The dependent claims relate to advantageous embodiments.

[0007] According to one aspect of the present disclosure, there is provided a method for coating a large area glass substrate, comprising: a) applying a water-soluble layer to at least one first predetermined area of ​​a surface of the glass substrate, wherein at least one second predetermined area of ​​the surface of the glass substrate remains free of the water-soluble layer; b) coating the surface of the glass substrate with at least one water-insoluble layer; and c) removing the water-soluble layer, wherein steps a) to c) are performed multiple times in succession.

[0008] The above-mentioned method in the automotive field allows only structured coating to be realized. In other words, partial areas of the substrate are sputter (or ion beam) coated after step c), while masked partial areas remain uncoated. When the method is repeated according to one aspect of the present disclosure (iterative method), several different sputter layers (depending on the number of iterations) can be arranged on the substrate (e.g., red, green and blue filters (RGB) after three iterations).

[0009] The different embodiments may preferably implement the following features:

[0010] The water-soluble layer is preferably not a photoresist.

[0011] The water-soluble layer is preferably water-soluble. Alternatively, the water-soluble layer can be removed using an additional solvent (e.g., alcohol). In other words, the water-soluble layer does not have to be limited to being water-soluble.

[0012] The glass substrate is preferably 1 mm 2 ~60m 2 , preferably 19m 2 ~60m 2 , particularly preferably 19m 2 ~39m 2 It has an area of.

[0013] The size of the so-called tape measure (standard dimensions in the coating industry) for the glass substrate is preferably 3.21 m x 6.00 m. Alternatively, the glass substrate may be sized 3.21 m x 12 m or even 3.21 m x 18 m. The lower dimension can be limited by the spacing of the transport rollers. The typical minimum dimension of the glass substrate is 1 m x 1 m.

[0014] The coating step is preferably carried out immediately after the step of applying the water-soluble layer.

[0015] In other words, preferably, no further method steps, such as exposure and development, are carried out after application and before coating of the water-soluble layer. This also eliminates the use and disposal of photoresist and developer chemicals. However, after application and before coating of the water-soluble layer, a specific drying step can be carried out to dry the water-soluble layer. In other words, preferably, at least the exposure and / or development steps are not carried out after application and before coating of the water-soluble layer.

[0016] The application of the water-soluble layer is preferably carried out by means of a printing process, in particular by means of a screen printing process, an offset printing process, a rotary printing process or a digital printing process.

[0017] The water-soluble layer preferably has a higher surface tension compared to the surface energy of the glass substrate, so as to produce hydrophobic glass substrate properties. For example, the surface energy of refined soda glass is about 47 mJ / m 2 Therefore, the surface tension of the water-soluble coating is preferably >60 mJ / m 2 The present disclosure is not limited to this preferred example, and other ratios of surface tensions are possible.

[0018] Furthermore, the surface tension can be optimized within wide limits using corresponding additives.

[0019] The water-soluble layer preferably contains a water-soluble ink, preferably a water-soluble ink in which a colorant is dissolved, and particularly preferably a pigment ink dispersed in water.

[0020] Preferably, the method comprises, prior to step a), a step of reducing the surface energy of the surface of the glass substrate, the step of reducing the surface energy of the surface of the glass substrate preferably comprising plasma polymerisation of hexamethyldisiloxane.

[0021] Coating the surface of the glass substrate preferably involves a directional coating method, preferably sputtering or ion beam coating.

[0022] Removal of the water-soluble layer preferably includes removal of the water-soluble layer and any water-insoluble layers located over the water-soluble layer.

[0023] The removal of the water-soluble layer is preferably carried out using a solvent, preferably a water-containing liquid.

[0024] The water-insoluble layer also preferably overlies at least a portion of the water-soluble layer after coating and mixes with the solvent when the water-soluble layer is removed using the solvent.

[0025] The step of removing the water-soluble layer preferably comprises filtering the water-insoluble layer in a solvent.

[0026] The removal of the water-soluble layer is preferably assisted by mechanical methods, preferably brushing.

[0027] Preferably, the method comprises the step of cleaning the surface of the glass substrate before applying the water-soluble layer.

[0028] The first and second predetermined regions in a subsequent execution of steps a)-c) preferably differ at least in part from a previous execution of steps a)-c) in order to position a plurality of structures, preferably optical filters, adjacent to one another. [Brief description of the drawings]

[0029] The above mentioned aspects are explained in more detail below with reference to exemplary embodiments and drawings, in which: [Figure 1a-d] 1 is a schematic diagram of method steps of a method according to one embodiment of the present disclosure. [Figure 1e-h] 4 is a schematic diagram of a further method step of a method according to an embodiment of the present disclosure. [Diagram 2] 1 is a flow chart according to an embodiment of the present disclosure.

[0030] Figures 1a)-d) show steps of a method according to one embodiment of the present disclosure. As can be seen in Figure 1a), a printing ink 20 is applied in a first step to a glass substrate 10 at predefined locations. According to Figure 1b), a material 30 is applied. Thus, the material 30 is located on the glass substrate 10 (at exposed locations) and on the printing ink 20. In a further step according to Figure 1c), the printing ink 20 is separated from the glass substrate 10 by water or another solvent. In the process, the material 30 located on the printing ink 20 is also peeled off. The material 30 located on the glass substrate 10 remains on the glass substrate 10, thus forming the desired structure on the glass substrate 10, as shown in Figure 1d).

[0031] Further details and examples of the above steps of Figures 1a)-d) are described below.

[0032] According to the present disclosure, the structured optical layer 30 is manufactured on a large area (glass substrate 10), for example by replacing a microlithography process with the direct printing of a water-soluble ink on a large substrate 10 (e.g., 3.21 m x 6 m). After cleaning the glass substrate 10, a water-soluble layer 20 is printed (e.g., by screen printing, digital printing, etc.) on the areas where the optical layer 30 is not desired. After a masking step, the printed circuit board 10 is provided with the optical layer 30 (e.g., sputtering, evaporation, etc.). After coating, the substrate 10 is washed again, whereby the masking layer 20 underneath the optical coating 30 dissolves in water and the optical layer 30 located thereon is likewise removed. Now the optical layer 30 is located on the substrate 10 on the previously unprinted areas. The previously masked areas on the substrate 10 are devoid of the optical coating 30.

[0033] In contrast to methods in electronics, the present method is carried out on significantly larger substrate sizes (square meters) and requires different structure precision (approximately 100 μm). Furthermore, in the method of the present invention, the masking is printed directly and does not have to be produced in a complex manner by coating with photoresist, exposing and developing.

[0034] To improve separation of the ink 20 after coating, the following advantageous embodiments of the masking ink, substrate material and coating method can be used.

[0035] In order to achieve the steepest possible edges, the printing ink 20 can be hydrophobic rather than wetting the glass substrate 10. Physically, this means that the printing ink 20 has a high surface tension. As a result of this property, a high contact angle is achieved during printing and thus a steep "masking edge" that is not covered with the coating material 30 during the subsequent coating. In addition, the masking ink 20 can be water-soluble and can be easily removed during the coating process, especially for vacuum coating methods (pressures <10 -3mbar), the action of plasma, UV radiation and temperatures between 50° C. and 80° C. are particularly suitable. Pigment inks dispersed in water are particularly suitable, which leave a chalky layer after evaporation of the water, which can be separated with water after coating. To achieve sufficient opacity, it is advantageous to increase the pigment or extender content of the printing ink 20 until a sufficient degree of coverage of the substrate 10 by the ink 20 is achieved. Alternatively, water-soluble inks with dissolved colorants are also conceivable, which have the same properties (opacity, surface tension).

[0036] Alternatively or additionally, to achieve the mentioned high contact angles, the surface energy of the surface to be coated may be reduced by a suitable coating (e.g., by plasma polymerization of hexamethyldisiloxane (HMDSO)).

[0037] To avoid the situation where the steeply shaped edges of the masking go uncoated, a "highly directional" coating method is suitable, preferably sputtering or ion beam coating. Isotropic coating methods such as atomic layer deposition (ALD) or plasma-enhanced chemical vapor deposition (PECVD) are less suitable.

[0038] Equally high demands are preferably made on the process step of separating the printing ink 20 (FIG. 1c) together with the overlying coating 30. On the one hand, the printing ink 30 should be completely dissolved so that the overlying coating 20 is completely separated from the substrate 10. If this is done by means of mechanical support (e.g. brushing), the ink 20 should be removed without mechanically damaging the underlying substrate 10 and the coating 30 remaining on the substrate 10 (scratches, breakouts at the edges of the coating structure) or even separating them.

[0039] The process steps of separation can include, for example: 1. A solvent (preferably water) is sprayed or poured onto the substrate 10. To accelerate the process, the solvent can be warm (e.g. 30° C.). 2. The solvent is left on the substrate 10 until the printing ink 30 underneath the coating 20 is dissolved as much as possible. 3. The solvent with the partially dissolved printing ink 30 and the coating 20 thereon is rinsed with more solvent and the residue is completely removed with a soft roller brush (long thin bristles).

[0040] After successful removal of the printing ink 20 from the substrate 10, the printing ink is dissolved in the solvent. In addition, there are solvent parts of the coating 30 that have been separated by the dissolution of the printing ink 20 from the substrate 10. These very small parts (~ about 10 μm to 100 μm) should not reach the substrate 10 so as not to deposit or dry (adhere) on the substrate 10. To avoid a high concentration of these coating particles in the solvent, they can preferably be continuously filtered out of the solvent. In addition to water-soluble substances, alternative solvents (such as, for example, alcohols) can also be used for the lift-off process (FIG. 1c).

[0041] As shown in the exemplary embodiment according to FIG. 1, in a first step (FIG. 1a)), a glass substrate 10 is partially printed (masking) with a water-soluble substance 20. In a second step (FIG. 1b)), the partially printed substrate 10 is coated with a layer 30 (for example an interference layer system). This interference layer system 30 can perform various functions (low-e, AR, dichroic filter or mirror, etc.). After coating (FIG. 1c)), the printed substance 30 is dissolved in a cleaning process and removed together with the interference layer system deposited thereon (lift-off). A substrate partially coated with the interference layer system remains (FIG. 1d)).

[0042] Figures 1e)-h) show further steps of the method according to one embodiment of the present disclosure, which substantially correspond to a repetition of the steps of figures 1a)-d), but preferably the areas where the printing ink 20 and / or the application material 31 according to figures 1e)-h) have been applied are at least partially different from the areas or materials 30 of the steps of figures 1a)-d).

[0043] As can be seen in FIG. 1e), the printing ink 20 is applied in a subsequent step of the step of FIG. 1d) to a predetermined location of the glass substrate 10 (here at the location of the first interference layer system 30). According to FIG. 1f), a material 31 is applied, preferably a material 31 different from the material 30 from the steps of FIGS. 1a)-d). Thus, the material 31 is placed on the glass substrate 10 (at the exposed locations, e.g. at the locations where the material 30 is not placed) and on the printing ink 20. In a further step according to FIG. 1g), the printing ink 20 is separated from the glass substrate 10 by water or another solvent. In the process, the material 31 located on the printing ink 20 is also peeled off. The material 31 located on the glass substrate 10 remains on the glass substrate 10 and thus forms the desired structure on the glass substrate 10, as shown in FIG. 1h). Preferably, the areas with the material 31 are adjacent to the areas with the material 30. However, material 31 may be in an area separate from material 30, ie, material 31 may not be adjacent (or may only be partially adjacent) to material 30.

[0044] The steps and conditions listed above with reference to Figures 1a)-d) apply equally to the steps of Figures 1e)-h) and are not repeated at this point.

[0045] 2 shows a flow chart with steps S101-S103 of a method for coating a large area glass substrate according to an embodiment of the present disclosure. The method according to FIG.

[0046] S101: Applying a water-soluble layer to at least one first predetermined area of ​​a surface of a glass substrate, while leaving at least one second predetermined area of ​​the surface of the glass substrate free of the water-soluble layer.

[0047] S102: Coating the surface of the glass substrate with at least one water-insoluble layer.

[0048] S103: The water-soluble layer is removed.

[0049] Steps a) to c) are preferably carried out consecutively multiple times.

[0050] In one embodiment, the glass substrate is 1 mm 2 ~60m 2 , preferably 19m 2 ~60m 2 , particularly preferably 19m 2 ~39m 2 It has an area of.

[0051] In one embodiment, the coating step occurs immediately after the step of applying the water-soluble layer.

[0052] In one embodiment, the application of the water-soluble layer is carried out by a printing method, in particular by a screen printing method, an offset printing method, a rotary printing method or a digital printing method.

[0053] In one embodiment, the water soluble layer has a higher surface tension compared to the surface energy of the glass substrate such that hydrophobic glass substrate properties are produced.

[0054] In one embodiment, the water-soluble layer contains a water-soluble ink, preferably a water-soluble ink having a dissolved colorant, most preferably a pigmented ink dispersed in water.

[0055] In one embodiment, the method comprises, prior to step a), a step of reducing the surface energy of the surface of the glass substrate, the step of reducing the surface energy of the surface of the glass substrate preferably comprising plasma polymerization of hexamethyldisiloxane.

[0056] In one embodiment, coating the surface of the glass substrate comprises a directional coating method, preferably sputtering or ion beam coating.

[0057] In one embodiment, removal of the water-soluble layer includes removal of the water-soluble layer and a water-insoluble layer located over the water-soluble layer.

[0058] In one embodiment, the removal of the water-soluble layer is carried out using a solvent, preferably a water-containing liquid.

[0059] In one embodiment, the water-insoluble layer also overlies at least a portion of the water-soluble layer after coating and mixes with the solvent when the water-soluble layer is removed using the solvent.

[0060] In one embodiment, removing the water-soluble layer comprises filtering the water-insoluble layer in a solvent.

[0061] In one embodiment, the removal of the water-soluble layer is assisted by mechanical methods, preferably brushing.

[0062] In one embodiment, the method includes cleaning the surface of the glass substrate before applying the water-soluble layer.

[0063] In one embodiment, in order to position multiple structures, preferably optical filters, adjacent to one another, the first and second predetermined regions in a subsequent execution of steps a)-c) are at least partially different from a previous execution of steps a)-c).

[0064] While the present disclosure has been illustrated and described in detail by means of the drawings and the associated description, the drawings and the detailed description are to be understood as illustrative and exemplary, and not restrictive of the present disclosure. It is understood that changes and modifications may be made by those skilled in the art without departing from the scope of the following claims. In particular, the present disclosure also includes embodiments having any combination of the features mentioned or shown above with respect to the various aspects and / or embodiments.

[0065] The present disclosure also includes individual features of the drawings even if they are shown in conjunction with other features and / or not described above.

[0066] Moreover, the word "comprise" and its derivatives do not exclude other elements or steps. Similarly, the indefinite articles "a" or "an" and their derivatives do not exclude a plurality. The functions of several features recited in a claim may be fulfilled by one unit. Also, the terms "substantially", "around", "approximately" and the like in conjunction with a property or value in particular precisely define the property or precisely the value. Any reference signs in the claims should not be understood as limiting the scope of the claim.

Claims

1. A method for coating a large area glass substrate (10), comprising the steps of: a) applying a water-soluble layer (20) to at least one first predetermined area of ​​a surface of a glass substrate (10), wherein at least one second predetermined area of ​​the surface of the glass substrate (10) remains free of the water-soluble layer (20); b) coating the surface of the glass substrate (10) with at least one water-insoluble layer (30); c) removing the water-soluble layer (20); Including, The method according to claim 1, wherein steps a) to c) are carried out consecutively multiple times.

2. The glass substrate (10) is 1 m ２ ~60m ２ , preferably 19 m ２ ~60m ２ , particularly preferably 19 m ２ ~39m ２ The method of claim 1 , wherein the area of ​​the surface is

3. 3. The method according to claim 1 or 2, wherein the coating step is performed immediately after the step of applying the water-soluble layer (20).

4. The method according to any one of claims 1 to 3, wherein the application of the water-soluble layer (20) is carried out by a printing method, in particular by a screen printing method, an offset printing method, a rotary printing method or a digital printing method.

5. The method according to any one of claims 1 to 4, wherein the water-soluble layer (20) has a surface tension higher than the surface energy of the glass substrate such that hydrophobic glass substrate properties result.

6. The method according to any one of claims 1 to 5, wherein the water-soluble layer (20) contains a water-soluble ink, preferably a water-soluble ink with dissolved colorant, particularly preferably a pigmented ink dispersed in water.

7. 7. The method according to any one of claims 1 to 6, comprising, prior to step a), a step of reducing the surface energy of the surface of the glass substrate (10), said step of reducing the surface energy of the surface of the glass substrate (10) preferably comprising plasma polymerization of hexamethyldisiloxane.

8. The method according to any one of the preceding claims, wherein the coating of the surface of the glass substrate (10) comprises a directional coating method, preferably sputtering or ion beam coating.

9. The method according to any one of claims 1 to 8, wherein removing the water-soluble layer (20) comprises removing the water-soluble layer (20) and the water-insoluble layer (30) located on the water-soluble layer (20).

10. The method according to any one of the preceding claims, wherein the removal of the water-soluble layer (20) is carried out using a solvent, preferably a water-containing liquid.

11. 11. The method of claim 10, wherein the water-insoluble layer (30) is also located on at least a portion of the water-soluble layer (20) after the coating and mixes with the solvent when the water-soluble layer (20) is removed with the solvent, and the step of removing the water-soluble layer (20) comprises filtering the water-insoluble layer (30) in the solvent.

12. The method according to any one of the preceding claims, wherein the removal of the water-soluble layer (20) is assisted by mechanical methods, preferably brushing.

13. The method according to any one of the preceding claims, comprising the step of cleaning the surface of the glass substrate (10) before applying the water-soluble layer (20).

14. 14. The method according to any one of claims 1 to 13, wherein the first and second predetermined regions in a subsequent execution of steps a) to c) are at least partially different from a previous execution of steps a) to c) in order to arrange a plurality of structures, preferably optical filters, adjacent to one another.

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