Method for manufacturing an electronic device

Abstract

The invention relates to a method for producing an electronic device (1, 2, 9), comprising providing a carrier substrate (3); applying aqueous cleaning ink droplets (4) in a first area (5) forming a first pattern on the carrier substrate (3) in an orderly manner by means of a printing technique; applying a metallization portion (7, 8) on the carrier substrate, so that in a second area (6) forming a second pattern, outside the first area (5) forming the first pattern, a metal (8) is deposited on the carrier substrate (3) in the form of a regular, metallic, continuous network, wherein the first area (5) forming the first pattern and the cleaning ink droplets (4) are provided. The first area (5) forms regular islands within a regular, metallic continuous network; in the first area (5) forming a first pattern, metal (7) is deposited above the cleaning ink droplets (4); the cleaning ink droplets (4) in the first area (5) and the metal (7) on the first area (5) are removed, so that the carrier substrate (3) obtained has such properties that it has no metallization in the first area (5) forming the first pattern and has a transparent conductive metallization in the second area (6) forming the second pattern, and the metallization is in the form of a regular continuous network.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electronic device. Background Art

[0002] Electronic devices, in particular semiconductors, solar cells or electrodes are obtained, for example, by lift-off methods known in the field of semiconductor production. In lift-off methods, the soluble coating is usually structured by exposing it to light in regions and then structuring it in a further step. Methods for finely structuring vapor-deposited materials are known in the literature, for example see KDM Rao, C. Hunger, R. Gupta, GU Kulkarni, M. Thelakkat: "A cracked polymer templated metal network as a transparent conducting electrode for ITO-free organic solar cells", Phys. Chem. Chem. Phys., 2014, Vol. 16, pp. 15107-15110, and S. Kiruthika, R. Gupta, KDM Rao, S. Chakraborty, N. Padmavathy, GU Kulkarni: "Large area solution processed transparent conducting electrode based on highly interconnected Cuwire network", J. Mater. Chem. C, 2014, Vol. 2, pp. 2089-2094.

[0003] According to the above document, a coating is first applied to the film, which forms a large number of cracks when drying. These cracks form a continuous network of dense mesh. In the subsequent vapor deposition of the material, the material is stored both on the coating (that is, above) and in the cracks. When removing the coating, for example by cleaning with a suitable solvent, the vaporized material above the coating is also removed. Usually only the vaporized material present in the crack lines remains.

[0004] Kulkarni et al. mentioned alternative solutions for manufacturing transparent electrodes in their article "Towards low-cost transparent conducting electrodes" in Current opinion in Chemical Engineering, 8:60-68 in May 2015.

[0005] WO 2016 / 192858 A1 describes a further developed method for manufacturing an electronic device, which is based on the idea of ​​using the technology known in the field of manufacturing security elements for valuable documents to finely structure the metallization to provide an electronic device. The technology mainly includes the use of (photo) anti-corrosion paint, the use of corrosive media and the use of cleaning ink (or ink that can be cleaned). According to the method described in WO 2016 / 192858 A1, a crack-forming coating is applied to a carrier substrate, the crack-forming coating is dried, wherein the coating forms a large number of cracks in the form of a continuous network of dense mesh when drying, and the metallization is applied to the carrier substrate, so that the metal material is deposited on the carrier substrate inside the cracks of the coating provided with cracks.

[0006] In the production described in WO 2016 / 192858 A1, the formation of cracks in the crack-forming coating applied before metallization is achieved statistically or randomly, so that depending on the material properties of the crack-forming coating, the drying parameters and the layer thickness of the crack-forming coating, a metal network structure with random metal line profiles and with random network geometry is obtained. In the production method described in WO 2016 / 192858 A1, a targeted metal line profile cannot be achieved. Summary of the invention

[0007] The technical problem to be solved by the present invention is to improve the production method known in the prior art.

[0008] This object is achieved according to the invention by the combination of features defined in the independent claims. Further developments of the invention are the subject matter of the dependent claims. SUMMARY OF THE INVENTION

[0010] 1. (First aspect of the present invention) A method for manufacturing an electronic device (1, 2, 9), comprising the following steps:

[0011] A) providing a carrier substrate (3);

[0012] B) applying aqueous cleaning ink droplets (4) in a sequential manner by printing technology on the carrier substrate (3) in a first area (5) forming a first pattern (or visual object);

[0013] C) applying the metallization (7, 8) on the carrier substrate, so that

[0014] - in the second areas (6) forming the second pattern, outside the first areas (5) forming the first pattern, metal (8) is deposited on the carrier substrate (3) in the form of a regular, metallic, continuous network, wherein the first areas (5) forming the first pattern with the washing ink droplets (4) form regular islands within the regular, metallic, continuous network;

[0015] - depositing metal (7) above the cleaning ink droplets (4) in the first area (5) forming the first pattern;

[0016] D) removing the washing ink droplets (4) in the first region (5) and the metal (7) located on the washing ink droplets, so that the carrier substrate (3) obtained has such properties that it:

[0017] - having no metallization in the first region (5) forming the first pattern;

[0018] - In the second areas (6) forming the second pattern there is a transparent conductive metallization in the form of a regular continuous network.

[0019] 2. (Preferred design) A method according to item 1, wherein step B) is implemented with the aid of a printing cylinder having a cell grid or a printing plate having a cell grid, i.e. aqueous cleaning ink droplets (4) are applied to a carrier substrate (3) in an orderly manner in a first area (5) forming a first pattern by printing technology, wherein the geometry of the metallization portion in the form of a regular continuous network generated in the method is determined by appropriately selecting parameters such as the cell layout, the cell geometry with respect to the planar dimensions, the cell depth and the web width.

[0020] 3. (Preferred design scheme) A method according to item 2, wherein the printing cylinder or printing plate has a plurality of different cell grid areas, wherein the cell grid areas differ in at least one of the parameters of the cell layout, the cell geometry related to the plane dimensions, the cell depth and the web width, so that the metallization part in the form of a regular continuous network produced in the method has a plurality of metallization part areas corresponding to the plurality of different cell grid areas, and the metallization part areas have different transparency and / or conductivity.

[0021] 4. (Preferred design scheme) A method according to one of items 1 to 3, wherein the aqueous cleaning ink droplets (4) in step B) are based on an aqueous cleaning ink having an adhesive, wherein the adhesive is preferably a polymer and the polymer is particularly preferably selected from hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, especially low molecular weight and medium degree of hydrolysis, polyvinyl pyrrolidone, polyethylene glycol and casein.

[0022] 5. (Preferred embodiment) The method according to any one of items 1 to 4, wherein the aqueous washing ink droplets (4) applied to the carrier substrate (3) are dried between steps B) and C).

[0023] 6. (Preferred embodiment) The method according to any one of items 1 to 5, wherein, in step A), a film or a multilayer structure is provided as a carrier substrate.

[0024] 7. (Preferred embodiment) The method according to any one of items 1 to 6, wherein the carrier substrate provided in step A) is transparent.

[0025] 8. (Preferred embodiment) The method according to any one of items 1 to 7, wherein the metallization in the form of a regular continuous network is subsequently removed in specific areas by means of a laser beam.

[0026] 9. (Preferred design) A method according to one of items 1 to 8, wherein the line width of the regular continuous metallization network is selected so that the human eye cannot distinguish the individual lines in the plane, but the difference relative to the untreated carrier substrate can be recognized by the human eye in both reflected light and transmitted light. DETAILED DESCRIPTION OF THE INVENTION

[0028] The invention is based on the idea of ​​using the technology known from the field of production of security elements for value documents using washing inks for fine structuring of metallizations in order to provide electronic devices.

[0029] It is known to have a security element with a symbol that can be visually recognized in transmitted light and, if necessary, also in reflected light. The symbol can have any form, such as numbers, letters, patterns, geometric or graphic views, etc., and is usually called "negative font" regardless of its form. The security element is manufactured, for example, by providing a transparent substrate with a coating, generally a metal coating (or metallization), and then removing the coating at a determined position. If the security element is facing the light, the area with the metal coating or other coating appears dark. On the contrary, the area where the coating is removed appears bright or at least significantly brighter than the area with the coating, depending on the transparency of the substrate. The more transparent the substrate is, that is, the stronger the light transmittance, the more prominent the contrast between the area with the coating and the area without the coating. In a very transparent substrate, the negative font can be clearly identified not only in transmitted light, but also in reflected light.

[0030] In the vapor deposition process, a metal coating is formed substantially all over. In the simplest case, a gap can be provided inside the metal coating by using a partition or a shielding plate during the vapor deposition process. This measure only realizes a roughly structured metallization. However, visually beautiful anti-counterfeiting elements require fine structuring. Finely structured metallizations can be realized, for example, by a so-called cleaning method. A cleaning method is described in WO 99 / 13157A1, in which a carrier film is printed in the form of a symbol by a printing ink having a high pigment content, coated with a thin cover layer (e.g., made of aluminum) and then removed by cleaning with a liquid to remove the printing ink and the cover layer above it, so as to produce an area in the form of a symbol without a coating.

[0031] WO 92 / 11142A1 (corresponding to EP 0516790 A1) or its German priority application DE 4041025A1 discloses printing inks that can be activated by heat, such as wax-containing emulsions. When heated, this emulsion softens and thus reduces the adhesion to the carrier film, so that in these areas with poor adhesion, the softened printing ink and the layer located thereon are removed by mechanical treatment, such as ultrasound, brushing or grinding. In addition, inks with foaming additives are disclosed as activatable printing inks, as they are common in the manufacture of foam materials. These foaming agents decompose gases under the action of heat and produce foam structures. The volume of the printing ink is thereby increased, thereby reducing the adhesion on the carrier film and the layer located above the printing ink is arched outward, so that they provide good action points for mechanical removal.

[0032] WO 97 / 23357 A1 refers to EP 0516790 A1 and also discloses activatable printing inks which are activated, ie washed, by treatment with suitable solvents.

[0033] The invention is based on the knowledge that in tests with solvent-containing cleaning ink compositions, the wetting of the carrier substrate to be wetted deteriorates as the water content of the cleaning ink increases. Surprisingly, such a soluble state can be produced by suitable selection of the water content, wherein the cleaning ink can be applied to the carrier substrate by printing technology in the form of a relatively vertical grid, which grid does not extend further due to the surface energy ratio. The webs of the printing cylinder used or the printing plate used separate the cleaning ink drops, which are printed on the carrier substrate geometrically corresponding to the cells of the printing cylinder or the printing plate. This is followed by a metallization step. In the cleaning step, the cleaning ink drops and the metal located thereon are removed together, and after the cleaning step, the webs of the printing cylinder or the printing plate correspond to the metal lines of the metal network.

[0034] In the cleaning step, the solubility of the binder, in particular the polymer, contained in the cleaning ink in the cleaning medium is utilized. The metal deposited on the cleaning ink area is removed together with the binder and other particles that may be contained in the cleaning ink in the cleaning process. The carrier substrate remains, on which the vapor-deposited metal network remains largely intact in the areas that were not previously coated with the cleaning ink.

[0035] The geometry of the metal network produced in the method can be controlled by suitable selection of the parameters of the cell layout or grid, the cell geometry with respect to the planar dimensions (i.e. the dimensions, for example the length and width of the respective cells in the plane of the printing plate or printing cylinder), the cell depth, the shape of the cells in the depth and the web width. The metal network obtained according to the method according to the invention does not have a statistical or random network structure, but rather a defined metal network structure with a defined metal line width and a defined metal line structure. In this way, metal network structures with freely selectable transparency and freely selectable electrical conductivity can be produced. Since the printing cylinder used or the printing plate used can have a plurality of areas with different cell layouts and / or cell geometries, metal network structures with areas of different network properties, in particular different transparency and / or different electrical conductivity, can be produced without any problems.

[0036] As regards the binder contained in the cleaning ink, in principle one of the materials used in the prior art cited above for the cleaning method is suitable. Particularly advantageous for the method according to the invention are polymers which have good solubility both in water and in organic solvents, usually alcohols and / or esters. Examples of such binders are hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, polyvinyl alcohols, especially of low molecular weight and with a moderate degree of hydrolysis, polyvinyl pyrrolidone, polyethylene glycol and casein.

[0037] The achievable metal line width at the end of the production method is preferably in the range of 1 μm to 50 μm, wherein the lines are usually so thin that they can only be recognized as lines using a magnifying glass. In a flat surface, the human eye cannot distinguish the individual lines, but can recognize the difference with respect to an untreated or coarser carrier substrate both in reflected light (or reflection) and in transmitted light (or transmission). By varying the island size The reflectivity or light transmittance can be adjusted in a suitable manner.

[0038] Compared to conventional, all-round and very thin metal layers with constant optical reflection and transmission (hereinafter also referred to as "translucent metallization"), the network structure of the metallization according to the invention is advantageous in terms of significantly higher chemical resistance. The metal is present in the metal lines in a "normal" layer thickness, while conventional translucent metallizations are very thin and therefore susceptible to corrosion, especially in the case of Al and Cu.

[0039] The metallization according to the invention in the form of a regular, densely meshed, continuous network shows electrical conductivity and optical transmission comparable to that of a full-scale ITO layer. Here, the fine metal wires can be used in combination with conventional embossing lacquers, conventional primer compositions and conventional heat-sealing lacquers and used as reflectors.

[0040] According to a preferred embodiment for producing an electronic device, aqueous cleaning ink droplets are applied in an orderly manner by printing technology in a first area forming a first pattern on a carrier substrate, such as a glass substrate, a film or a multilayer structure. The term "orderly" means that the individual cleaning ink droplets are regularly spaced apart. The application by printing technology can preferably be carried out by means of a (engraved) intaglio printing plate, which has individual cells at regular intervals. Alternatively, there may be individual cell groups, for example a group of seven hexagonally arranged cells, wherein the cell groups are arranged at regular intervals from one another. Instead of a printing plate, a printing cylinder may also be used. Thereafter, the metallization is applied, so that in the second region forming the second pattern, outside the first region forming the first pattern, metal is deposited on the carrier substrate in the form of a regular, metallic, continuous network, wherein the first region forming the first pattern with the washing ink droplets forms regular islands within the regular, metallic, continuous network. In the first region forming the first pattern, metal is deposited above the washing ink droplets. Thereafter, the washing ink droplets in the first region are removed together with the metal located on the washing ink droplets, so that the carrier substrate obtained has such properties that it has no metallization in the first region forming the first pattern and has a transparent, conductive metallization in the form of a regular, continuous network in the second region forming the second pattern.

[0041] If necessary, the carrier substrate provided with the metal network structure can be provided with a continuous metallization in other areas, which is used, for example, for electrical contact. It is also possible to overlay coating with a metal having a color different from that of the metal of the metal network structure. In this case, the observer may see mixed colors. In further processing, additional primer layers and / or heat-sealing lacquer layers can be used. By applying additional effect layers, other optical effects, such as fluorescence, can also be achieved without any problem, because the reflector used, i.e. the metal network structure, only exists on a partial surface.

[0042] The method for removing the cleaning ink is advantageously achieved by dissolving with a suitable solvent. Here, for example, water, an aqueous solution, a mixture of a solvent and water, optionally with a surfactant, optionally with a defoamer and other additives are used. The separation or dissolution can also be assisted by a nozzle or mechanically by a brush, a roller or by a felt. The choice of solvent is suitably coordinated with the coating. In addition to water, the following solvents can usually be used: methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methoxypropyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, methylene chloride, chloroform, toluene, xylene, methanol, ethanol, 2-propanol. In addition, acetal or a mixture of the above solvents can be used.

[0043] General Notes:

[0044] The metallization of the electronic device according to the invention can be based on a single metal. Suitable metals are, for example, aluminum, silver, copper, nickel, iron, chromium, cobalt, gold, titanium, tin, zinc or alloys of one or more of the aforementioned elements (e.g., iron-silicon alloys). In addition, the metallization can be based on a multilayer metallization, which can be obtained, for example, by gradual vapor deposition. An advantageous multilayer metallization is, for example, a Cr layer followed by an Al layer. The adhesion of the Al layer to the layer structure is improved by the Cr layer.

[0045] Furthermore, the electrical conductivity of the metallization according to the invention in the form of a regular, close-meshed, continuous network is improved by the additional application of a conductive polymer. Suitable conductive polymers are, for example, conductive polymers based on thiophene, such as poly-3,4-ethylenedioxythiophene (PEDOT or PEDT). Alternatively, inorganic, transparent and conductive layers can be applied, such as metal oxides, such as titanium dioxide, indium tin oxide or fluorine tin oxide. These additional layers can also be used to controllably change the electrical properties of the metallization according to the invention, such as the work function.

[0046] The transparent conductive metallization obtained in the production method according to the invention in the form of a regular, close-meshed, continuous network can subsequently be removed in certain areas by means of a laser beam (so-called laser demetallization). In this way, the transparent conductive metallization is structured, i.e., free spaces or demetallized areas can be provided.

[0047] Further exemplary embodiments and advantages of the invention are explained below with reference to the drawings, in which the figures are not shown to scale or to proportion in order to improve the clarity. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In the attached picture:

[0049] Figure 1 shows a first electronic device according to the invention in 25 times magnification;

[0050] Figure 2 shows a first electronic device according to the invention in 100 times magnification;

[0051] Figure 3 shows a second electronic device according to the invention in 25 times magnification;

[0052] Figure 4 showing a second electronic device according to the present invention at 100 times magnification; and

[0053] Figures 5 to 8 The production of an electronic device according to the invention is shown. DETAILED DESCRIPTION

[0054] Figure 1 A photograph of a first electronic device 1 according to the invention is shown in a top view at 25 times magnification. The electronic device is obtained by using a gravure printing plate with cells. The cleaning ink used for applying aqueous cleaning ink drops by printing technology is based on the adhesive polyvinyl pyrrolidone. After the vapor deposition of the metallization, for example an Ag layer, a cleaning step with an aqueous cleaning solution is carried out. On a carrier substrate, for example polyethylene terephthalate (PET), a transparent, conductive metallization in the form of a regular, continuous network remains. On Figure 1 The advantageous, targeted metal line contours can be seen in FIG. 1 , which represent the webs of the gravure printing plate used during production.

[0055] Figure 2 A photograph of a first electronic device 1 according to the invention is shown in a top view at 100 times magnification.

[0056] Figure 3A photograph of a second electronic device 2 according to the invention is shown in a top view at 25 times magnification. The electronic device 2 is obtained essentially according to the same production method as the electronic device 1 described above, wherein in the case of the second electronic device 2 according to the invention, a different gravure printing plate with a greater web width is used for applying the aqueous washing ink drops by printing technology.

[0057] Figure 4 A photograph of a second electronic device 2 according to the invention is shown in a top view at 100 times magnification.

[0058] Figures 5 to 8 The production according to the invention of an electronic device 9 is illustrated in each case in a cross-sectional view.

[0059] according to Figure 5 , a carrier substrate 3, such as a polyethylene terephthalate (PET) film, is provided.

[0060] according to Figure 6 , aqueous washing ink drops 4 are applied sequentially by printing technology in first areas 5 forming a first pattern on the carrier substrate 3. Second areas 6 forming a second pattern are intended for later formation of a transparent conductive metallization in the form of a regular continuous network.

[0061] according to Figure 7 , metallizations 7, 8 are applied to the carrier substrate 3, so that in the second areas 6 forming the second pattern, outside the first areas 5 forming the first pattern, metal 8 is deposited on the carrier substrate 3 in the form of a regular, metallic, continuous network, wherein the first areas 5 forming the first pattern with the washing ink drops 4 form regular islands within the regular, metallic, continuous network. In the first areas 5 forming the first pattern, metal 7 is deposited above the washing ink drops 4.

[0062] Subsequently, the cleaning ink droplets 4 in the first region 5 are removed together with the metal 7 located thereon.

[0063] Figure 8 The product 9 of the manufacturing method according to the invention is shown. The carrier substrate 3 obtained has such properties that it has no metallization in first areas 5 forming a first pattern and has a transparent conductive metallization in the form of a regular continuous network in second areas 6 forming a second pattern.

Claims

1. A method for manufacturing an electronic device (1, 2, 9), comprising the following steps: A) providing a carrier substrate (3); B) applying aqueous cleaning ink droplets (4) in a first area (5) forming a first pattern on a carrier substrate (3) in an orderly manner by printing technology, wherein the aqueous cleaning ink droplets (4) in step B) are based on an aqueous cleaning ink having an adhesive, wherein the adhesive is a polymer and the polymer is selected from hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol and casein; C) Applying a metallization on a carrier substrate, so that - in the second area (6) forming the second pattern, outside the first area (5) forming the first pattern, metal is deposited on the carrier substrate (3) in the form of a regular, metallic, continuous network, wherein the first area (5) forming the first pattern with the washing ink droplets (4) forms regular islands within the regular, metallic, continuous network; - depositing metal over the washing ink droplets (4) in the first area (5) forming the first pattern; wherein the aqueous washing ink droplets (4) applied to the carrier substrate (3) are dried between steps B) and C); D) removing the washing ink droplets (4) in the first region (5) and the metal on the washing ink droplets in a washing step, so that the carrier substrate (3) obtained has such properties that: - having no metallization in the first region (5) forming the first pattern; - In the second areas (6) forming the second pattern there is a transparent conductive metallization in the form of a regular continuous network.

2. The method according to claim 1, wherein: Step B), i.e. the orderly application of aqueous washing ink drops (4) in a first area (5) forming a first pattern to a carrier substrate (3) by means of a printing cylinder with a cell grid or a printing plate with a cell grid, is carried out, wherein the geometry of the metallization produced in the method in the form of a regular continuous network is determined by the selection of at least one of the parameters of the cell layout, the cell geometry with respect to the planar dimensions, the cell depth and the web width.

3. The method according to claim 2, wherein: The printing cylinder or the printing plate has a plurality of different cell grid areas, wherein the cell grid areas differ in at least one parameter of the cell layout, the cell geometry with respect to the planar dimensions, the cell depth and the web width, so that the metallization produced in the method in the form of a regular continuous network has a plurality of metallization areas corresponding to the plurality of different cell grid areas, the metallization areas having different transparency and / or conductivity.

4. The method according to any one of claims 1 to 3, wherein: The aqueous washing ink droplets (4) in step B) are based on an aqueous washing ink having a binder, wherein the binder is a polymer and the polymer is polyvinyl alcohol having a low molecular weight and a medium degree of hydrolysis.

5. The method according to any one of claims 1 to 3, wherein: In step A), a film or a multilayer structure is provided as a carrier substrate.

6. The method according to any one of claims 1 to 3, wherein: The carrier substrate provided in step A) is transparent.

7. The method according to any one of claims 1 to 3, wherein: After step D), the metallization in the form of a regular, continuous network is removed in specific areas by means of a laser beam.

8. The method according to any one of claims 1 to 3, wherein: The line width of the regular, continuous metallization network is selected such that the human eye cannot distinguish individual lines in the plane, but a difference with respect to an untreated carrier substrate is recognizable for the human eye both in reflected light and in transmitted light.

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