Method for producing functional structure and functional structure

Abstract

The invention relates to a method for producing a functional structure, comprising the following steps: providing a base body of the functional structure; according to the invention, at least one metal layer is applied to a surface of the substrate, said surface of the substrate having, at least in some regions, one or more anchoring elements which are designed and arranged to improve the adhesion of the metal layer to the surface relative to the adhesion of the metal layer to the surface without the anchoring elements.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a functional structure, the method having the following steps:

[0002] Providing a substrate for the functional structure;

[0003] Applying at least one metal layer to the surface of the substrate. Background Art

[0004] Such a functional structure is, for example, a waveguide for guiding electromagnetic waves. Electromagnetic waves, especially high-frequency signals, can either propagate in space or in a waveguide device. Such a waveguide device is provided with a conductive structure that includes a spatial region, thereby forming a spatial path or channel for guiding electromagnetic waves or high-frequency signals or for manipulating electromagnetic waves or high-frequency signals in space or in a frequency range.

[0005] When manufacturing high-frequency components, especially for generating cavities, the component consists of two halves for manufacturing reasons. The cavities thus produced, for example, milled into a metal substrate, result in the true functionality of the high-frequency component. The high-frequency component can be, for example, a waveguide, a so-called hollow conductor, but can also be a filter, a resonator, a coupler, or an antenna.

[0006] Such high-frequency components can be produced from a plastic substrate. For subsequent functionality, the high-frequency component must be provided with a conductive coating. The prior art is to electroplate or electroless plate with metal. This is also carried out, for example, in decorative coatings (Plating on Plastics (PoP)), where different layer systems are used, for example, layer systems using Cu, Ni, Cr, Au, Ag, etc. and combinations and / or sequences of these elements.

[0007] The conductivity and properties of the surface of the component interacting with electromagnetic waves are necessary. In particular, the inner wall of the formed cavity must be conductive. Manufacturing components from metal or a conductive base material is not only cost-intensive but also time-consuming, which especially requires a cost-intensive CNC milling process. In this context, the following solution has been followed in the prior art: Instead, such components are made of plastic and only made conductive in one or more subsequent steps. Known processes propose chemical methods here, such as electroplating or electroless plating the surface of the substrate with metal.

[0008] The metallization of plastics, especially photopolymers, presents technical challenges especially with regard to the adhesion of the metal layer to the plastic surface. In principle, the metal layer has poor adhesion to photopolymers. The adhesion of the metal layer deposited on other plastics may also be insufficient, especially those other plastics having a low roughness, for example having an R q3D printable or 3D printed plastics with a roughness of <20μm.

[0009] Thus, according to the prior art, a body made of a photopolymer undergoes a costly process of sulfonation of the surface to be metallized in order to achieve better adhesion of the metal layer on the surface.

[0010] It is also known to use a cladding method with hexavalent chromium. However, due to the harmful nature of hexavalent chromium, the cladding method is subject to strict legal restrictions or prohibitions.

[0011] In addition, pickling with hexavalent chromium, for example pickling with chromium sulfate, results in a significant increase in surface roughness, which is ultimately one of the mechanisms that promotes adhesion strength.

[0012] Regarding the previously known methods, there is a desire to further simplify the cladding method in order to particularly improve the adhesion strength. Summary of the Invention

[0013] Against this background, the object on which the present invention is based is to provide a method improved in the above-mentioned manner.

[0014] The object is achieved by a method having the features of independent claim 1. Advantageous refinements of the invention are the subject matter of the dependent claims.

[0015] Accordingly, according to the present invention, it is proposed that the surface of the substrate has at least locally one or more anchoring elements, which are configured and arranged to improve the adhesion of the metal layer on the surface relative to the adhesion of the metal layer on a surface without anchoring elements.

[0016] The metal layer can also be electrically conductive.

[0017] Particularly preferred is an embodiment of the method, in which the substrate is integral, i.e., made in one piece and consists of only one material, preferably manufactured by an additive method, the metal layer is applied in a wet-chemical manner, and a further metal layer is applied by an electroplating process, wherein the functional structure is preferably an especially slotted hollow conductor or waveguide. Preferably, the surface of the layer, especially the functional surface, is smoothed by an electroplating process.

[0018] However, the functional structure can also be a component consisting of multiple parts, where one or more parts are manufactured by the method according to the present invention.

[0019] For example, the adhesion, in particular the adhesion strength, of a coating to a substrate can be tested or estimated by a scratch test in accordance with DIN EN ISO 20502:2016-11 (English: Scratch Test), by a Rockwell indentation test in accordance with DIN EN ISO 26443:2016-09 or in accordance with VDI 3824-4, by a grid cutting test in accordance with DIN EN ISO 2409:2020-12, by a grid cutting test and / or a cross-cut test in accordance with DIN EN ISO 16276-2:2007-08, by a tear test in accordance with DIN EN ISO 4624 or by a similar test method. It is also possible to test by applying a fabric tape and tearing the fabric tape, wherein the tearing force is sensed or measured.

[0020] Preferably, improved adhesion should be understood as meaning that, relative to the adhesion of a layer applied to a surface of a substrate without anchoring elements, at least one of the test methods mentioned gives better results or better test values when testing the adhesion of a layer applied to a surface of a substrate with anchoring elements.

[0021] The surface area to which the layer is applied is preferably enlarged by the anchoring elements, and / or a form-fitting connection is preferably formed between the substrate and the layer by the anchoring elements. Thereby, the physical or chemical adhesion and / or the mechanical adhesion of the layer to the substrate is improved.

[0022] Preferably, it is proposed that one or more anchoring elements comprise or are recesses that penetrate into the surface and / or protrusions that project from the surface, and / or have undercuts, and / or are produced by the roughness of the surface.

[0023] The surface preferably has flat areas and areas provided with anchoring elements. The undercut of an anchoring element, which is particularly configured as a recess, should preferably be understood as meaning that a line perpendicular to the flat area starting from the undercut penetrates the substrate. Thus, the undercut forms a kind of barb by which the layer is connected to the substrate in a form-fitting manner.

[0024] The anchoring elements can have any shape. For example, the anchoring elements can be provided in a marbleized form.

[0025] The recesses and / or protrusions can have the shape of heaps, sharp corners, etc.

[0026] A conceivable geometry of an anchoring element with an undercut is, for example, a recess with a conical cross-section, wherein the recess widens in the depth direction.

[0027] Other conceivable geometries of the anchoring elements are cylinders, triangles, tetrahedrons, blocks, trapezoidal blocks, spheres or sphere-like shapes and freely formed shapes of any kind.

[0028] It is also conceivable that during manufacturing, the geometry of the anchoring element changes relative to the desired geometry. Thus, distortion or growth may occur. However, the anchoring element preferably serves the purpose of increasing the adhesion strength. Adhesion and adhesion strength should preferably be understood synonymously.

[0029] The preferably spatially extended portion of the anchoring element facing the surface is for a surface that interacts with electromagnetic waves, preferably according to the wavelength of the electromagnetic wave λ_0 = c_0 / f and / or according to the wavelength λ_g = 2*pi / β guided in the hollow conductor, where β is the phase parameter of the hollow conductor. β = 2*pi*f / (c0*sqrt(epsr))sqrt(1-(f_c / f) 2 ), where f_c = c0 / (2*w), where w = the width of the hollow conductor.

[0030] The anchoring elements each have an extension, preferably in the propagation direction of the electromagnetic wave, and the extension is less than the entire wavelength of the electromagnetic wave, especially less than half of the wavelength of the electromagnetic wave, preferably less than a quarter of the wavelength of the electromagnetic wave.

[0031] It is conceivable that on non-HF-related surfaces, the spatial dimensions of the anchoring elements are also significantly increased.

[0032] It is conceivable that a plurality of anchoring elements are arranged on the surface uniformly or non-uniformly, where the anchoring elements have the same shape, or at least one anchoring element has a different shape.

[0033] It is conceivable that the anchoring elements are produced by a 3D printer.

[0034] In other words, there can be different areal densities of the anchoring elements on the surface, that is, the number of anchoring elements per unit area.

[0035] The areal density can be changed according to the frequency range of the electromagnetic waves to be conducted via the functional structure that is pursued. The higher the applied frequency, the higher the areal density can be, and the smaller the extension of the anchoring element facing the surface can be.

[0036] An areal density of more than one anchoring element per square centimeter, especially more than one anchoring element per square millimeter, is advantageous, and / or where the areal density is preferably at most 100,000, preferably 40,000, especially 10,000 anchoring elements per square millimeter.

[0037] The areal density can also be less than 100 or less than 10 anchoring elements per square millimeter.

[0038] It is conceivable that the anchoring elements are produced during the manufacture of the substrate or are placed or introduced at or into the substrate after manufacture.

[0039] In a particularly preferred variant of the method, the surface provided with the anchoring element also remains a continuous surface. Thus, the anchoring element is preferably surrounded by a surface that defines the function of the component.

[0040] This preferably enables a basic manufacturability that is largely independent of the orientation in the 3D printing structure space, where the quality of the surface can also be changed without supporting the individual anchoring elements.

[0041] Furthermore, the outermost regions of the surfaces that determine the function of the HF component are preferably maintained with high quality, since the roughness is not unnecessarily increased there, for example by erosive chemical pickling.

[0042] It is conceivable to coat the surface with at least one anchoring element with a metal layer by means of different methods, such as by means of PVD, CVD, sputtering, inkjet, aerosol jet, nano jet, roll-to-roll printing, screen printing, physical coating with ink or paste or paint, chemical methods by means of wet chemical deposition or electroplating deposition.

[0043] In particular, electroless deposition and electroplating deposition of the metal layer are advantageous.

[0044] It is conceivable to arrange the anchoring element on an arbitrary 3D printed surface in order to increase the adhesion strength of the metal layer deposited thereon.

[0045] However, preferably, the substrate is an HF component, in particular an HF component based on the technical design of a slotted hollow conductor. The slotted hollow conductor is preferably a hollow conductor in which openings are provided in the outer wall, the openings not causing radiation. This is the case when the openings are small relative to the wavelength of the wave and / or the current density associated with the wave in the conductive wall does not intersect transversely to its direction of flow.

[0046] In an advantageous embodiment, it is proposed to apply the metal layer by means of a preferably electroless, wet chemical process, preferably by wetting a part or the entire surface of the substrate with a dispersion containing micron and / or nano particles, where the micron and / or nano particles preferably have nickel, copper, silver, gold, zinc, tin, chromium, palladium and / or platinum.

[0047] It is preferably proposed to coat the metal layer by means of one of the following methods: PVD, CVD, sputtering, inkjet, aerosol jet, nano jet, roll-to-roll printing, screen printing, physical coating with ink or paste or paint, chemical methods by means of wet chemical deposition or electroplating deposition.

[0048] Particles with an average particle size D50 of less than 1 μm can be referred to as nanoparticles, and particles with an average particle size D50 of greater than or equal to 1 μm can be referred to as microparticles. Nanoparticles can have an average particle size D50 of 10 nm to 300 nm, preferably 10 nm to 100 nm. Microparticles can have an average particle size D50 of 1 μm to 100 μm, preferably 1 μm to 5 μm or 10 μm. The particle size preferably relates to the equivalent diameter of the corresponding particles.

[0049] The layer that can conduct electricity is preferably a layer having a metal. The layer that can conduct electricity can also be non-conductive after application and / or become non-conductive after application.

[0050] The substrate can determine the shape for the functional structure.

[0051] The particles are preferably composed of one or more metals or have one or more metals.

[0052] The particles can be plastic-coated.

[0053] In the sense of the present invention, "electricity" forms the superordinate concept of electrical and / or electronic.

[0054] Preferably, it is proposed that when manufacturing a functional structure for an electrical device, first, a substrate that determines the shape of the functional structure is realized. The material for manufacturing the substrate is preferably non-conductive. However, in order to implement the method, a conductive or semi-conductive material can also be used equally well to manufacture the substrate.

[0055] The metal coating of the substrate is preferably realized by wetting at least a part, preferably the entire surface of the substrate, with a dispersion containing conductive microparticles and / or nanoparticles. The dispersion can be an ink having microparticles or nanoparticles. The material used (ink) is preferably a material that realizes high conductivity. The dispersion or ink is preferably water-based, and an organic separating agent can also be provided. Alternatively or additionally, a solvent can be added. Conceivable particles are aluminum, silver, gold, tin, zinc, or copper particles or mixtures composed of them. The dispersion or ink is coordinated with the surface energy of the substrate material used, such as plastic, so as to facilitate full wetting of the surface. In addition, the viscosity of the dispersion or ink material can be coordinated with the smallest openings present in the substrate structure to ensure wetting by the dispersion.

[0056] After the solvent / water evaporates / volatilizes, the surface of the substrate is wetted with the ink material, and a conductive coating is formed by optional post-treatment, preferably sintering. Therefore, the new method is an alternative to chemical, non-electrolytic coatings. Thus, preferably, the substrate body is functionalized, i.e., for electrical components, in such a way that the substrate body is coated completely or partially with a conductive ink material.

[0057] Contrary to chemical coating methods in which a substrate is introduced into a reagent solution and a chemical reaction is induced between the surface of the reagent solution and the substrate, this method instead uses a dispersion for coating, which physically wets the substrate and forms a conductive coating by post-treatment.

[0058] Compared with chemical coating methods, by the method according to the invention, a smoother surface structure of the coated substrate can be achieved, which brings decisive advantages especially in components of high-frequency technology. The smoother the surface of the component, the better the subsequent electrical conductivity of the component. Due to the required pretreatment, the chemical processes of the existing methods usually cause an unfavorable roughening of the substrate surface.

[0059] The method according to the invention can be advantageously used, for example, for manufacturing electrical components, wherein the functional structure of the component is formed by the coated substrate. Some of the functional structures in the functional structure require a spatial region surrounded by a conductive structure for guiding electromagnetic waves. In such cases, the substrate is provided with corresponding structures at the sites required for the electrical function, where the mechanical function or the electrical function is required or only less restricted for the mechanical function or the electrical function.

[0060] Coating and wetting are preferably carried out by completely immersing the substrate into a dipping bath containing the corresponding dispersion. In principle, immersing the substrate once is sufficient. By immersing multiple times, a better distribution of the dispersion around or through the substrate, especially in optionally existing cavities, is ensured. An ultrasonic bath containing the dispersion is preferably used. After immersion into the dipping bath, the substrate can be shaken briefly to remove the excess dispersion.

[0061] As an alternative to the dipping bath, the dispersion can also be applied by means of an aerosol chamber, in which the dispersion atomized into droplets wets the substrate. There is also the possibility of coating or wetting the substrate by spraying or pouring with the dispersion.

[0062] It is conceivable to apply a metal layer by means of aerosol spraying or nano-spraying.

[0063] It is also conceivable to apply the dispersion by means of rinsing.

[0064] After applying the dispersion, the quality and conductivity of the coating can be manufactured or improved by thermally post-treating the substrate surface or the adhered micron or nanoparticle. For this purpose, drying, preferably drying in a circulating air system, sintering in an oven, UV treatment, delivery of hot air, or infrared irradiation are provided. The thermal post-treatment can have a positive effect on the conductivity of the applied coating. Thus, high conductivity of the resulting surface coating is achieved by subsequent sintering of the micron or nanoparticle, for example, sintering in a hot oven. The sintering temperature of the ink material is coordinated with the glass transition temperature of the plastic used so that the ink material is not damaged.

[0065] It can be proposed not to perform thermal post-treatment on the substrate, especially not drying.

[0066] It can also be advantageous to perform surface pretreatment of the substrate before applying the dispersion in order to achieve surface cleaning or surface activation, in particular, for optimized adhesion of the coating.

[0067] During the coating process, especially when introduced into the corresponding immersion bath, it is crucial that the corresponding dispersion can reach all the inner surfaces of the walls to be coated. Therefore, in order to promote liquid circulation, it can also be advantageous to design the substrate such that the substrate material is present only where mechanical or electrical functions are required or only slightly restricts the mechanical or electrical functions, that is, only certain walls of the substrate are constructed there from the beginning, or voids are provided for the walls afterwards. This makes it easier for the dispersion to advance into the cavity. In addition, the viscosity of the dispersion or ink material used should be coordinated with the smallest openings present in the substrate structure to ensure circulation.

[0068] In the case of a rectangular hollow body or cavity, the walls corresponding to the side walls of a substrate integrated waveguide (SIW) known from the prior art can be implemented discontinuously because the openings do not impair the high-frequency technology function or electrical function, which is also known from the prior art. For example, the walls on the narrow side of the cavity are slotted, while the walls on the wide side of the rectangular hollow body can be implemented without corresponding openings.

[0069] In another advantageous embodiment, it is proposed to apply a metal layer by means of a wet chemical process, preferably by electroless deposition of nickel, copper, silver, gold, tin, zinc, etc. on a surface having at least one anchoring element.

[0070] Furthermore, in an advantageous embodiment, it is proposed that the electrolessly coated metal layer on the surface with at least one anchoring element is subsequently expanded with at least one additional metal layer by an electrochemical method and / or an electroplating method. Here, the electroplated metal layer imitates the surface as well as the anchoring element, and after the electroplated coating, the latter remains visible.

[0071] In another advantageous embodiment of the method, it is proposed that the electrolessly coated metal layer on the surface with at least one anchoring element is subsequently expanded with at least one additional metal layer by an electrochemical method and / or an electroplating method. Here, the electroplated layer is deposited such that the anchoring element is enclosed or completely covered by the layer.

[0072] Another advantageous embodiment of the method provides that the electroplated deposition of one or more metal layers is carried out such that effective smoothing of the outermost surface is achieved, as is carried out in DE 10 2021 128 881A1. Thereby, the loss of electromagnetic waves is reduced.

[0073] As already mentioned above, the substrate can be made of a non-conductive material. Here, ceramics or plastics have proven to be particularly suitable. The plastic can be a polyamide, preferably PA6, PA11 or PA12. The plastic can in particular be a photopolymer. Here, polyurethane or acrylate can be included in the plastic material. It can also be proposed that the substrate is a hollow body and its inner side is coated with a metal layer.

[0074] Preferably, it is proposed that the method includes the following additional steps:

[0075] Applying at least one additional metal layer to the substrate by means of an electroplating process or a wet chemical process.

[0076] The one or more applications of the additional metal layer preferably result in functional smoothing of the surface of the layer.

[0077] A functionally smooth surface is preferably understood to mean that the layer is configured such that the function of the layer is not impaired. If the function of the layer is the conduction of electromagnetic waves, the surface of the layer that is functionally smooth for the wave conduction function is configured such that the wave conduction is not impaired by the anchoring element.

[0078] Thus, the anchoring element or the microstructure can also be optically visible on the surface that is functionally smooth for the wave conduction function. The surface provided with the anchoring element can be called a microstructure.

[0079] Smoothing the surface or the microstructure is preferably carried out to reduce electromagnetic losses or to reduce the attenuation of the electromagnetic waves conducted through the functional structure.

[0080] In a preferred embodiment, it is proposed that after applying one or more layers, the one or more layers cover the anchoring element(s) such that the layer(s) has / have a preferably functional, smooth, flat and / or continuous surface, where the anchoring element(s) is / are preferably visible, partially visible or invisible.

[0081] The shape of the anchoring element(s) can also be partially recognized.

[0082] As an example, a recess serving as an anchoring element can also be filled with a layer such that the recess is still visible. However, the recess can also be filled with a layer such that the layer completely fills the recess, thereby making the layer invisible.

[0083] As an example, a recess serving as an anchoring element can also be overgrown by a layer deposited thereon, where the recess is filled, for example, in the manner of a lead seal. However, an overgrown layer can also be deposited such that a cavity remains.

[0084] Another preferred embodiment of the method proposes an anchoring element, such as a small tower, protruding beyond the surface, which is covered by a metal layer such that the anchoring element disappears beneath the metal layer.

[0085] Due to the continuous surface, manufacturability on the overhanging areas is also maintained, and the surface preferably has the same shape as before the layer was applied. In particular, the expected high-frequency functionality of the surface is also retained because the anchoring element(s) does / do not interact with electromagnetic waves or interact with electromagnetic waves insignificantly.

[0086] It is conceivable that the anchoring element(s) is / are only provided on the functional surface of the substrate.

[0087] It is also conceivable that the anchoring element(s) is / are only provided on the non-functional surface of the substrate, or is / are only provided or also provided on the functional surface of the substrate, in particular on the inner side of a preferably slotted hollow conductor or on the radiation surface of an antenna.

[0088] In another preferred embodiment of the method, there is a distribution and shaping of the anchoring element(s) coordinated with the function of the surface. This means that a surface without high-frequency (HF) functionality can have anchoring elements in a more pronounced form, such as in the form of large holes and / or deep holes. On a surface with HF functionality, anchoring elements adapted to the frequency and application case, such as anchoring elements with a small spatial extent, can be introduced. However, it is also conceivable that a surface with HF functionality is implemented completely without anchoring elements.

[0089] In a preferred embodiment, it is proposed that the functional structure is configured to conduct electromagnetic waves, wherein the anchoring elements each have an extension, preferably in the propagation direction of the electromagnetic waves, and the extension is less than the entire wavelength of the electromagnetic waves, preferably less than half of the wavelength of the electromagnetic waves, preferably less than a quarter of the wavelength of the electromagnetic waves.

[0090] The dimensions of the anchoring elements, preferably the dimensions in the direction of the surface extension, can also follow the areal density in addition to the wavelength. It is conceivable here that at least one anchoring element is placed per square centimeter. An areal density of at least one anchoring element per square millimeter is particularly advantageous.

[0091] It is conceivable to smooth the outermost region, in particular by electroplating or smoothing the substrate before applying the layer.

[0092] It is conceivable that the substrate is manufactured by an additive method, where the additive method includes SLS, SLA, DLP, multi-jet, two-photon printing, aerosol jetting, inkjet, nano-jetting, FDM, SLM, and / or EBM.

[0093] Preferably, it is proposed that the substrate is at least partially or completely made of ceramic, plastic, in particular photopolymer, or metal, and / or the substrate is a hollow body, where the inner side of the hollow body is clad with a metal layer, and / or the substrate is formed or produced in one piece or in multiple pieces. The substrate can also be partially or completely made of a material for selective laser sintering.

[0094] In a preferred embodiment, it is proposed that the substrate is manufactured by an additive method, in particular by 3D printing, selective laser sintering or stereolithography, Multi-nozzle or by a casting method, in particular by injection molding.

[0095] The anchoring elements are preferably produced during the manufacture of the substrate, rather than being individually placed or introduced into the substrate or into the substrate. This is particularly conceivable when manufacturing the substrate by an additive method. However, in principle, it is also conceivable to individually place or introduce the anchoring elements to manufacture the substrate. It is also conceivable that the anchoring elements are prepared by 3D printing and then formed by subsequent process steps.

[0096] It is preferably proposed that the functional structure is or includes an electrical functional structure or a high-frequency technology functional structure, a high-frequency line, in particular preferably a slotted hollow conductor, or an antenna, in particular a horn antenna or a helical antenna, or a filter or a resonator or a coupler or other passive HF components, or is or includes a component of a solar installation, a solar cell, a touch screen, smart glass, a wearable device or an LED, or is or includes a Molded Interconnect Device (MID) or a Mechatronic Integrated Device (MID) or a decorative structure.

[0097] The invention also relates to a high-frequency technology functional structure, which is partially or completely manufactured by means of the method according to the invention, and which has at least one metal layer on the surface of the substrate provided with the anchoring elements.

[0098] It is conceivable that one or more anchoring elements include or are recesses that penetrate into the surface and / or protrusions that protrude from the surface, and / or have undercuts, and / or are formed by the roughness of the surface.

[0099] It is conceivable that one layer or multiple layers cover the anchoring elements such that the layer has a preferably functionally smooth, flat and / or continuous surface, wherein the anchoring elements are preferably visible, partially visible or invisible.

[0100] It is conceivable that the anchoring elements are only provided on the non-functional surface of the substrate, or are only provided or also provided on the functional surface of the substrate, in particular on the inner side of a preferably slotted hollow conductor or on the radiation surface of an antenna.

[0101] The features described herein are preferably not only features of the product but also features of the method, with necessary modifications. In other words, the features of any one of claims 1 to 17 can also be the subject matter of the functional structure according to any one of claims 18 to 20.

[0102] It should be noted here that the terms "a" and "an" do not necessarily refer to exactly one element in the components, even if this is a feasible embodiment, but can also represent multiple elements. Similarly, the use of the plural also includes the existence of the components involved in the singular form, and vice versa, the singular also includes multiple elements among the components involved. In addition, all the features of the invention described herein can be combined with each other arbitrarily or claimed in isolation from each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Other advantages, features, and effects of the present invention are derived from the following description of preferred embodiments with reference to the accompanying drawings, in which the same or similar components are denoted by the same reference numerals. Shown herein:

[0104] Figure 1 A perspective view showing an embodiment of the functional structure according to the present invention.

[0105] Figure 2 A perspective view showing the surface of an embodiment of the functional structure according to the present invention.

[0106] Figure 3 A perspective view showing the surface of an embodiment of the functional structure according to the present invention.

[0107] Figure 4 A perspective view showing the surface of an embodiment of the functional structure according to the present invention.

[0108] Figure 5 A cross-sectional view showing an embodiment of the functional structure according to the present invention.

[0109] Figure 6 A perspective view showing another embodiment of the functional structure according to the present invention.

[0110] Figure 7 A perspective view showing another embodiment of the functional structure according to the present invention.

[0111] Figure 8 A perspective view showing another embodiment of the functional structure according to the present invention.

[0112] Figure 9 A cross-sectional view showing another embodiment of the functional structure according to the present invention.

[0113] Figure 10 A graph showing the transmission performance of the functional structure according to the present invention. Detailed Description of the Invention

[0114] In Figure 1 an exemplary substrate 10 of the high-frequency technology functional structure according to the present invention is shown.

[0115] In Figure 1 the substrate 10 shown is a test body for measuring the adhesion of an electrically conductive layer on the substrate 10 and thus is provided with holes 2. Of course, the present invention is not limited to the substrate 10 in the form of a test body.

[0116] The substrate 10 provided with a metal coating can be fixed to the base through the holes 2, and then different test methods can be performed on the substrate to check or estimate the adhesion, especially the adhesion strength, of the coating on the substrate 10.

[0117] Now in Figures 2 to 4 a progressively magnified detail of the surface of the substrate 10 is shown. Figure 4 The maximum magnified portion of the surface of the substrate 10 is shown.

[0118] As can be seen from, for example, Figure 4 the surface of the substrate 10 is provided with recesses. The recesses 1 are arranged on the surface of the substrate 10 in a regular pattern, but may also be arranged irregularly. Similarly, the recesses 1 may have the same or respectively different shapes. There may also be provided a plurality of recesses 1 having one shape and further recesses 1 having different shapes. Thus, the recesses 1 may have any shape.

[0119] In Figure 5 a cross-section of the recess 1 can be seen. The recess 1 is circular at the surface and tapers outwards in the depth direction. Thereby, the recess 1 has an undercut with respect to the surface. Thereby, the recess 1 is designed in a cave-like manner.

[0120] In Figure 6 a substrate 10 for a slotted waveguide or a hollow conductor for guiding electromagnetic waves is shown. The substrate has two flanges and a channel for wave conduction.

[0121] Now in Figure 7 and Figure 8 progressively magnified details of the substrate 10 are shown. Figure 8 The maximum magnified portion of the surface of the substrate 10 is shown.

[0122] Recesses 1 are provided on the surface of the substrate 10, as can be seen particularly clearly from Figure 8 therein.

[0123] Similarly, the recesses 1 are provided on a surface parallel to the said surface, as can be seen from Figure 9 therein. The recesses 1 are circular at the surface and taper outwards in the depth direction. Thereby, the recesses 1 have an undercut with respect to the surface. Thereby, the recesses 1 are designed in a cave-like manner.

[0124] The two surfaces having the recesses are connected to one another by two slotted wall portions 3, thereby producing a channel for wave conduction. The wall portions have slits, whence the name slotted waveguide is derived.

[0125] The printed surface is not a sharp boundary between a dielectric, such as air and metal, but can be described as a gradual transition for the incident electromagnetic field.

[0126] The material transition corresponds to the cumulative frequency function of the surface profile, as can be seen from Figure 10 therein.

[0127] In Figure 10 the graph, the depth of the recess in nm is depicted on the abscissa, and the normalized conductivity, magnetic field, and loss power density are depicted on the ordinate. The solid line is the corresponding measured curve without the recess, and the dashed line is the corresponding measured curve with the recess. Curve 100 represents the conductivity, curve 200 represents the magnetic field, and curve 300 represents the loss power density.

[0128] Generating mechanical roughness by introducing holes of arbitrary shape mainly causes a change in the region behind the intermediate surface (depth > 0) of the function. Due to the low penetration depth of the electromagnetic field, for the transmission performance, essentially the region in front of the intermediate surface is important. Therefore, in this case, the mechanical roughness generated in this way is generated only in a form that minimally affects the electromagnetic field and the loss power density hardly changes, and thus this does not cause the transmission characteristics to deteriorate in the application.

[0129] The anchoring element can have an extension of less than 10 nm or less than 1 μm to about 2 μm - 3 μm, in particular less than 10 μm.

Claims

1. A method for manufacturing a functional structure, the method having the following steps: Providing a substrate for the functional structure; Applying at least one metal layer to the surface of the substrate, Characterized in that The surface of the substrate has at least locally one or more anchoring elements, which are configured and arranged to improve the adhesion of the metal layer on this surface relative to the adhesion of the metal layer on the surface without anchoring elements.

2. The method according to claim 1, wherein The one or more anchoring elements include or are recesses that penetrate into the surface and / or protrusions that protrude from the surface, and / or have undercuts, and / or are produced by the roughness of the surface.

3. The method according to claim 1 or 2, characterized in that, A plurality of anchoring elements are distributed on the surface uniformly or non-uniformly, wherein the anchoring elements have the same shape, or at least one anchoring element has a different shape.

4. The method according to any one of the above claims, characterized in that, The anchoring elements are produced by a 3D printer.

5. The method according to any one of the preceding claims, characterized in that, The areal density of the anchoring elements on at least one area of the surface is greater than one anchoring element per square centimeter, preferably more than one anchoring element per square millimeter, wherein the areal density is preferably at most 100,000, preferably 40,000, especially 10,000 anchoring elements per square millimeter.

6. The method according to any one of the preceding claims, characterized in that The anchoring elements are produced during the manufacture of the substrate or are placed or introduced at or into the substrate after manufacture.

7. The method according to any one of the above claims, characterized in that, The metal layer is applied by means of a preferably electroless, wet-chemical process, preferably by wetting the surface or the substrate with a dispersion comprising micron and / or nano particles, wherein the micron and / or nano particles preferably have nickel, copper, silver, gold, zinc, tin, chromium, palladium and / or platinum.

8. The method according to any one of the preceding claims, characterized in that, The metal layer is coated by one of the following methods: PVD, CVD, sputtering, inkjet, aerosol jet, nano jet, roll-to-roll printing, screen printing, physical coating with ink or paste or lacquer, chemical methods by wet-chemical deposition or electroplating deposition.

9. The method according to any one of the above claims, characterized in that, The method includes the following additional steps: Applying at least one additional metal layer to the substrate by means of an electroplating process or a wet-chemical process.

10. The method according to any one of the preceding claims, characterized in that, After applying one or more of the layers, one or more of the layers cover the anchoring elements such that the layer has a preferably functional, smooth, flat and / or continuous surface, wherein the anchoring elements are preferably visible, partially visible or invisible.

11. The method according to any one of the above claims, characterized in that, The anchoring elements are provided only on the non-functional surface of the substrate, or are provided only or also on the functional surface of the substrate, especially on the inner side of a preferably slotted hollow conductor or on the radiation surface of an antenna.

12. The method according to any one of the above claims, characterized in that, The functional structure is configured to conduct electromagnetic waves, wherein the anchoring elements each have an extension, preferably an extension in the propagation direction of the electromagnetic waves, the extension being less than the entire wavelength of the electromagnetic waves, preferably less than half of the wavelength of the electromagnetic waves, preferably less than a quarter of the wavelength of the electromagnetic waves.

13. The method according to any one of the above claims, characterized in that, Smoothing the outermost region, especially by electroplating or smoothing the substrate before applying the layer.

14. The method according to any one of the above claims, characterized in that, The substrate is manufactured by an additive method, wherein the additive method includes SLS, SLA, DLP, multi-nozzle, two-photon printing, aerosol jetting, inkjet, nano-jetting, FDM, SLM, and / or EBM.

15. The method according to any one of the above claims, characterized in that, The substrate is at least partially or completely composed of ceramic, plastic, in particular a photopolymer, or metal, and / or the substrate is a hollow body, wherein the inner side of the hollow body is clad with the metal layer, and / or the substrate is formed or produced in one piece or in multiple pieces.

16. The method according to any one of the above claims, characterized in that, The functional structure is or includes an electrical functional structure or a high-frequency technology functional structure, a high-frequency line, in particular a preferably slotted hollow conductor, or an antenna, in particular a horn antenna or a helical antenna, or a filter or a resonator or a coupler or other passive HF components, or is or includes a component of a solar installation, a solar cell, a touch screen, smart glass, a wearable device, or an LED, or is or includes a molded interconnect device (MID) or a mechatronic integrated device (MID) or a decorative structure.

17. A functional structure, the functional structure being manufactured partially or completely by means of the method according to any one of the preceding claims, the functional structure having at least one metal layer on the surface of the substrate provided with the anchoring elements.

18. The functional structure according to claim 17, wherein, One or more of the anchoring elements include or are recesses that penetrate into the surface and / or protrusions that protrude from the surface, and / or have undercuts, and / or are produced by the roughness of the surface.

19. The functional structure according to claim 17 or 18, characterized in that, One layer or multiple layers cover the anchoring elements such that the layer has a preferably functionally smooth, flat, and / or continuous surface, wherein the anchoring elements are preferably visible, partially visible, or invisible.

20. The functional structure according to any one of claims 17 to 19, characterized in that, The anchoring elements are provided only on the non-functional surface of the substrate, or are provided only or also on the functional surface of the substrate, in particular on the inner side of a preferably slotted hollow conductor or on the radiation surface of an antenna.

Images