Surface-structured substrate with a black marking region

Abstract

The invention relates to a surface-structured substrate. The surface-structured substrate has at least one first outer surface with a black marking region which is formed by a structured region and an unstructured region. The structured region has a first interference pixel which is made of a first periodic structure. The invention additionally relates to a method for producing a surface-structured substrate.

Description

[0001] Surface-structured substrate with a black marking area

[0002] TECHNICAL FIELD

[0003] The present invention relates to a surface-structured substrate, wherein the surface-structured substrate has at least one first outer surface with a black marking region, which is formed by a structured region and an unstructured region. The structured region has a first interference pixel formed from a first periodic structure. Furthermore, the invention relates to a method for producing a surface-structured substrate.

[0004] STATE OF THE ART

[0005] Industrial labels and markings are subject to increasingly stringent requirements, depending on their intended use. Particularly dark and high-contrast markings that remain stable under various viewing angles can be achieved using black marking, a laser processing technique that has the additional advantage of not ablating the surface of the material. Nanometer-scale structures are created using extremely short laser pulses, resulting in a permanent and deep blackening of the treated surface areas. Ultrashort-pulse lasers, which have a pulse duration in the picosecond or femtosecond range, can also be used to create corrosion-resistant markings, which are essential for medical devices such as surgical instruments or implants.

[0006] For example, CN 108436285 A discloses a laser marking device and method for black marking stainless steel. In the black marking method, the laser light emitted by an energy source is deflected by a galvanometer scanning system and then focused by an optical focusing mirror and directed onto the surface of a workpiece. The laser emits a laser pulse with a wavelength of 1064 ± 5 ​​nm, a pulse duration of 100-130 ns, and an average power of 20 W. WO 2018 / 189988 A1 describes a method for manufacturing a metal product in which black marking is also performed.The method includes scanning a base laser beam in a prescribed first direction while irradiating the base laser beam onto a surface of a laminated body, and repeating the scanning for a plurality of rows to form a base region on the surface of the laminated body. Further, scanning a marker laser beam in a prescribed second direction while irradiating the marker laser beam onto the surface of the laminated body, and repeating the scanning for a plurality of rows to form a black mark resulting from oxidation of the surface of the laminated body. The second direction is different from the first direction. An identification code having a prescribed pattern is formed by a combination of the base region and the black mark.

[0007] The disadvantage of the known methods is that they are comparatively slow, which severely limits the processing speed. This makes them very complex and therefore costly.

[0008] TASK

[0009] The present invention is therefore based on the technical object of providing a substrate with at least a first outer surface which has a black marking area, wherein the black marking area can be produced by a simple, cost-effective and effective method.

[0010] Furthermore, the present invention is based on the technical object of providing a durable, for example, under extreme temperature conditions and high stress, and a view-stable black marking area which has a high degree of absorption and a low degree of reflection of electromagnetic waves, in particular in the visible wavelength range.

[0011] Furthermore, it is an object of the present invention to provide a method with which such laser-surface-structured components can be manufactured in a targeted and reliably reproducible manner with predetermined properties. SOLUTION

[0012] The object is achieved by a surface-structured substrate having the features of claim 1 and a method having the features of the subordinate claims. Further advantageous embodiments can be found in the subclaims, the description, and the exemplary embodiments.

[0013] The object is achieved in particular by a surface-structured substrate, preferably a laser-surface-structured substrate, wherein the surface-structured substrate has at least a first outer surface with a black marking area.

[0014] The black marking region of the surface-structured substrate is formed by a structured and an unstructured region. According to the invention, the structured region has a first interference pixel, wherein the first interference pixel is formed from a first periodic structure comprising at least three surface irregularities that deviate from a flat surface. In this sense, the periodic structure is designed as a periodic, topographical structure. Such surface irregularities are changes in the surface, which can be designed as either depressions or elevations. In particular, they can be linear structures, i.e., groove-shaped depressions or groove-shaped elevations. Furthermore, such surface irregularities can be designed as point-shaped structures, in particular as inverse pegs or as pegs.Different types of surface irregularities can also be present simultaneously on a surface or on an interface.

[0015] In this case, a groove-shaped depression or a groove-shaped elevation has an extension in a first dimension that is significantly larger, preferably at least 10 times larger, than the extension in the other two dimensions. The groove-shaped depression or the groove-shaped elevation runs parallel to the surface having the structured region, in particular parallel to the first outer surface of the substrate or the cover layer.

[0016] The distance between two adjacent surface irregularities within an interference pixel, in particular within the first interference pixel, is a first interference period (p1). According to the invention, the first interference period, i.e., the period of the first periodic structure or the distance from a center point or a center line of a depression to a depression arranged adjacent to it in a period direction, is in the range from 50 nm to 200 pm, preferably in the range from 50 nm to 50 pm, particularly preferably in the range from 5 pm to 45 pm.

[0017] According to an advantageous embodiment, the first interference period is in the range from 10 pm to 35 pm, preferably in the range from 15 pm to 30 pm. The surface in the structured area appears black, which is referred to as black marking. With an interference period of less than 5 pm, so-called rainbow effects occur more frequently, in which undesirable color gradients are usually perceptible to the observer.

[0018] According to the invention, the structured region further comprises a plurality of mutually offset interference pixels, each comprising a periodic structure of at least three surface irregularities, wherein at least 50% of the mutually offset interference pixels have an overlap of at least 95%, preferably of at least 97%, particularly preferably of at least 99%, and most particularly preferably of at least 99.5% with a neighboring interference pixel, preferably with a plurality of neighboring interference pixels. This overlap can extend to one or more neighboring interference pixels. This arrangement enables improved optical properties by achieving an enhanced interference effect, which can influence the optical appearance of the substrate.The precise arrangement and high degree of overlap of the interference pixels allow for fine-tuned control of the light interference and ensures uniform light scattering in the structured area, which promotes / enhances the trapping effect and reduces glare, enabling more intense absorption of electromagnetic waves so that the.

[0019] The readability of the information displayed on the substrate is improved and / or the incorporation / application of immutable security features is improved. Furthermore, this overlap enables the creation of high-resolution optical effects that can be used in security technologies or display technology. The invention lies in the combination of high precision in the pixel arrangement with flexibility in the design of the size and shape of the pixels, which opens up new possibilities in the development of optical materials and systems.

[0020] The "overlap of interference pixels" is understood to mean the spatial overlap of two interference pixels, i.e. the area that two overlapping interference pixels have in common compared to the area contained by a single one of the two interference pixels. Since each interference pixel is formed by a pulse during application using laser interference structuring, this overlap is also referred to as pulse-to-pulse overlap. An interference pixel has an area defined by a circle formed by the outer edges of the surface irregularities. This circle is the largest circle that just touches or is tangent to one of the contained surface irregularities. In case of doubt, the size of the overlap is related to the interference pixel with the smaller area.

[0021] The overlapping interference pixels can have the same periodic structures, each consisting of at least three surface irregularities, in particular in the form of inverse cones, cones, groove-shaped depressions, or groove-shaped elevations, or they can differ from one another in their periodic structures. Thus, in one embodiment, the structured region can have a plurality of first interference pixels arranged offset from one another, or first and second interference pixels, wherein the periodic structures of the second interference pixels differ from the periodic structures of the first interference pixels. Likewise, third or further interference pixels with likewise differing periodic structures can be arranged offset from the first and / or second interference pixels.

[0022] The repetitively arranged interference pixels are first generated along a first row. A further row is then generated offset from the first row. The interference pixel-to-interference pixel overlap (also referred to herein as "pixel-to-pixel overlap" or "interference pixel overlap" or, when applied using laser pattern application methods, in particular using laser interference patterning, as "pulse-to-pulse overlap") is preferably very high within a row, i.e., preferably at least 95%, preferably at least 97%, while the overlap between the rows is low. This allows defined structures to be created quickly and effectively.

[0023] However, a high pixel-to-pixel overlap can also be created by generating a first row such that there is a smaller overlap, for example, in the range of 10% to 20%, or even no overlap at all. The row is then regenerated, with the position of the regenerated row having a large overlap of at least 95%, preferably at least 97%, with the previously generated row. The overlap can thus be created by rasterizing a row multiple times.

[0024] In multi-pulse processing, i.e. both in multiple irradiation and in the case of a large pulse-to-pulse overlap, incubation effects occur, so that the first pulse advantageously changes the absorption properties in such a way (e.g. by changing the roughness, etc.) that the second pulse nominally ablates somewhat more compared to if the first pulse had not occurred.

[0025] In addition, slight heating of the substrate can also lead to changes in ablation thresholds, ideally slightly increased, which is particularly relevant for pulse durations of over 500 ps.

[0026] The greater the overlap, the greater the structural depth of the resulting structures, in particular of the surface irregularities, and the more strongly the optical effects described herein can appear or be pronounced, in particular with regard to the black marking properties, whereby the structured area of ​​the black marking appears darker (and blacker) to an observer. The structural depth of the incorporated / applied periodic structures, for example the first periodic structure, i.e. the depth or height of the surface irregularities relative to the unstructured surface (projected surface) on the first outer surface, is preferably in the range from 0.3 pm to 60 pm, more preferably in the range from 0.5 pm to 40 pm. In order to achieve such structural depths, there is preferably an overlap of the interference pixels as defined herein. Structural depths of more than 1 pm have proven to be particularly advantageous.In various embodiments, the surface of a substrate having a black marking region has a structured region, wherein the structure depths of the periodic structure lie in a numerical range obtained by combining any two of the following endpoint values: 0.5 pm, 1 pm, 2 pm, 3 pm, 4 pm, 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, 10 pm, 11 pm, 12 pm, 13 pm, 14 pm, 15 pm, 16 pm, 17 pm, 18 pm, 19 pm or 20 pm. Most preferably in the range of 1 pm and 20 pm, most preferably in the range of 2 pm and 15 pm, most preferably in the range of 3 pm and 20 pm, even more preferably in the range of 5 to 20 pm. Due to the deeper structures, the trapping effect (as described herein) is pronounced, allowing for more intense absorption of electromagnetic waves, which results in the structured area of ​​the black mark appearing darker and thus more intensely black to an observer.This increases the readability and durability of markings applied to substrates. This opens up new possibilities in the development of products with special visual properties, such as in security technology or in the production of high-resolution displays. The combination of variable structure depth and a high degree of overlap thus leads to a substrate with expanded functional properties and applications as defined herein. Furthermore, the structured areas created here with a high structure depth are characterized by high resistance to wear effects, in particular high abrasion resistance and temperature resistance, so that the applied structures and structural features exhibit high dimensional stability and longevity.

[0027] Structuring using pulse-to-pulse overlap has the advantage that at least individual structural elements within a first, second, and / or further interference pixel are irradiated multiple times. This allows self-organization processes to form a quasi-periodic line structure superimposed on the periodic dot structure as a wave structure, in particular a so-called LIPSS. Advantageously, hierarchical structures can be created quickly and effectively on the substrate surface, allowing the surface roughness of the wall of a periodic dot structure to be increased, particularly in the nanometer and / or submicrometer range, resulting in an increase in the surface area.

[0028] The structured region is formed by the various applied structures. These can be a single line structure, a single dot structure, multiple superimposed line structures, multiple superimposed dot structures, or even superimposed dot and line structures. Even if the structured region consists of multiple, not necessarily interconnected, individual structured sub-regions, such as individual pegs or individual groove-shaped depressions, the entire portion of the surface that is structured, whose surface has consequently changed due to treatment using a laser interference process, is considered a structured region within the meaning of the invention. Thus, each surface can have only one structured region.

[0029] Any part of the surface that cannot be assigned to the structured area is then considered to belong to the unstructured area.

[0030] The period of the structure, i.e. the structure period, is called the interference period (p n ). It generally depends on the structuring of a mask, the negative of the desired periodic dot or line structure on a mold, or the wavelength of the interfering laser beams, the angle of incidence of the interfering laser beams, and the number of interfering laser beams. Further advantageous embodiments and developments emerge from the subclaims and from the description with reference to the figures.

[0031] GENERAL BENEFITS

[0032] With the aid of a structuring of surfaces and / or interfaces of substrates, in particular a cover layer and / or a base layer of substrates, as described herein, the optical properties of the surface or interface can advantageously be influenced in a targeted manner.

[0033] In particular, a black marking area can be applied to a surface or interface effectively and advantageously much faster than conventional methods. The resulting black marking also has a particularly matte finish. A combination with additional optical effects that appropriately influence the optical properties of the surface leads to reduced reflections and glare, thus creating synergistic effects.

[0034] Furthermore, the structure can be applied / created directly onto a substrate surface (i.e., without the need to apply the structure indirectly via another layer). Since the structuring is not dependent on the refractive index or the adhesion of specific coating materials to the substrate, this structure is more flexible than conventional chemical structuring or nanostructuring, which requires the application of metal gratings to the arrays.

[0035] The stability and robustness of the resulting structures are also advantageous, as they are improved compared to other processes, especially coatings. Thus, the durability of the laser-surface-structured component is optimized with specifically adjusted surface properties. The background here is that the structures are applied directly to the surface of a component's cover layer and / or incorporated into the component and cannot detach from the surface over time and under the material's usage-related stress, especially mechanical stress. Furthermore, the structures are chemically resistant to solvents and glass cleaners.

[0036] In contrast to conventional methods (such as etching, sandblasting, and polymer coatings) for applying a structure to a substrate, a further advantage of the surface-structured substrate or application process defined herein is that only certain sections / areas of a layer of a cover layer can be structured in a targeted and / or partial manner without great effort. This eliminates the need for the complex fabrication and placement of a mask for application to a surface to be structured, which, for example, shields / protects certain areas of the surface from treatment. Furthermore, the structural parameters (e.g., the interference period, the structure depth, the diameters, the shape, and the size of the depressions, especially the inverse cones or the groove-shaped depressions), and thus also the associated properties, can be adapted in a targeted and customized manner.

[0037] A further advantage is the possibility of achieving several of the advantageous properties simultaneously on a surface or at least on a component. For this purpose, either different structures, in particular periodic dot structures and / or periodic line structures, are superimposed on a surface and / or different surfaces or interfaces of a component can be structured.

[0038] DETAILED DESCRIPTION OF THE INVENTION

[0039] The surface-structured substrate according to the invention describes a substrate having at least one black marking area with at least one first periodic structure, in particular a dot structure, in the micrometer and / or submicrometer range, in particular with a plurality of periodic structures arranged offset from one another, which have an overlap of at least 95%, whereby a permanent and view-stable black marking area is created.

[0040] Structured substrate

[0041] For the purposes of the invention, the term “substrate” refers to a substrate (an object or a material) whose surface extends in multiple spatial directions. A substrate, preferably a flat substrate, can be a planar substrate or a curved substrate, for example a parabolic substrate. For the purposes of the invention, “flat” also means that the extension of a substrate, preferably a flat and / or transparent substrate, for example a planar substrate in the x and y directions, or the extension of a curved substrate along its radius of curvature, is greater than the extension of the region in which the at least three partial beams interfere with one another. In the case of a curved substrate with a curved first outer surface, the projected surface is then also curved.In a preferred embodiment, the substrate is a substrate whose extension in the x and y directions, or whose extension along a radius of curvature, is less than or equal to the extension of the region in which the at least three partial beams interfere with each other. Homogeneous structuring of the substrate is possible in one processing step (during a laser pulse).

[0042] In a particularly preferred embodiment, the substrate is a flat substrate whose extent in the x and y directions, or whose extent along a radius of curvature, is greater than the extent of the region in which the at least three partial beams interfere with each other. By moving the substrate in the x and y planes, a flat, homogeneous structuring of the substrate is possible in several processing steps (with several laser pulses). The movement of the substrate can be achieved by rotation or translation, or by a superposition of rotation and translation.

[0043] A structured substrate is characterized in particular by the fact that the substrate has a depth, also referred to as the substrate depth. The depth of the substrate is preferably greater, particularly preferably significantly greater, than the depth of the structures produced on the surface of the substrate, referred to herein as the structure depth. The structure depth is preferably less than 50% of the substrate depth, particularly preferably less than 25% of the substrate depth, very particularly preferably less than 10% of the substrate depth, further preferably less than 5% of the substrate depth, or less than 1% of the substrate depth, or less than 0.1% of the substrate depth. This preferably preserves the stability, i.e., the cohesion and fracture strength, of the structured substrate.

[0044] In a preferred embodiment, the black marking area is formed with a gloss factor of less than 10, preferably less than 5, particularly preferably less than 2.5, very particularly preferably less than 1, in particular less than 0.5, in particular less than 0.2, even more preferably less than 0.1. The gloss factor is preferably measured with a gloss meter at an angle of incidence of 60°.

[0045] In a particularly preferred embodiment, the gloss factor, preferably measured with a gloss meter at an angle of incidence of 60°, has a value in the numerical range obtained by combining any two of the following endpoint values: 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19 and 0.2. The technical advantages of this embodiment lie in the significant reduction in light reflection, which enables high optical absorption. This is particularly advantageous in applications where minimal light reflection is desired, such as in optical measurement, security technologies or display technology. Precise control of the gloss factor allows you to maximize optical contrast and improve the visual perception of the black mark.

[0046] A lower gloss factor leads to a more matt overall impression of the black marking due to the associated low reflection, which can advantageously increase the contrast between the black marking area and the adjacent non-structured surface of the substrate.

[0047] A surface-structured substrate with a black marking area preferably has a high black value in the black marking area. The black value of a substrate, or the surface of a substrate, is characterized by a high degree of absorption or a low degree of reflection of electromagnetic waves from the visible frequency spectrum in the range from 380 nm to 750 nm under normal lighting conditions. For the purposes of the invention, normal lighting conditions are understood to mean everyday lighting conditions during the day outdoors or in well-lit interiors, where "well-lit" means that light intensities of at least 300 lux are present.In particular, a substrate having a black marking region within the black marking region exhibits a reflection of electromagnetic waves from the visible frequency spectrum of less than 5%, preferably of less than 1%, particularly preferably of less than 0.5%, very particularly preferably of less than 0.05%. In particular, a substrate having a black marking region within the black marking region exhibits an absorption of electromagnetic waves from the visible frequency spectrum of more than 95%, preferably of more than 99%, particularly preferably of more than 99.5%, very particularly preferably of more than 99.95%.The combination of high absorption and low reflection achieves an exceptionally high color contrast between the black mark area and other areas of the substrate, which is advantageous for a wide variety of applications, including, but not limited to, optical markings and visual displays. The term "color contrast" herein refers to the degree of visual distinguishability based on the difference in color perception and brightness between the black mark area and the surrounding areas of the substrate, particularly the non-structured areas. This color contrast is caused by a significant difference in the spectral properties of light absorption and light reflection, with the black mark area characterized by significantly lower reflection and higher absorption in the visible range of the electromagnetic spectrum.A high color contrast, especially due to a low reflection of less than 5% in the black marking area, contributes to clear demarcation and improved visual recognition.

[0048] According to a particularly preferred embodiment, a structured substrate with a black marking region has at least two subregions (as defined herein) within the black marking region, the black values ​​of which differ. The subregions are preferably characterized by different structural periods, structural depths, and / or shapes, in particular by different structural depths, of the structural features contained therein. This allows for a gradual progression of the color contrast from non-structured regions of the substrate to the structured subregions of the substrate.

[0049] For the purposes of the invention, the term "substrate" encompasses a solid material with a reflective surface. Examples of such materials include metals, polymers, ceramics, and glasses.

[0050] For the purposes of the invention, the term substrate encompasses a solid material with a preferably reflective surface, wherein the substrate is solid in particular at room temperature, so that any introduced surface irregularities remain on the surface. Examples of such substrates are, in particular, metals and semiconductors or compounds thereof, in particular copper and silicon. Other materials, in particular those with a good specific thermal conductivity of at least 20 W / (m K), particularly preferably of at least 50 W / (m K), very particularly preferably of at least 75 W / (m K), in particular of at least 100 W / (m K), even more preferably of at least 150 W / (m K), measured at 20 °C, are also suitable for such applications.Examples of suitable metals include copper (Cu, 240-401 W / (m K)), silver (Ag, 429 W / (m K)), gold (Au, 314 W / (m K)), tin (Sn, 67 W / (m K)), zinc (Zn, 110 W / (m K)), aluminum (Al, 236 W / (m K)), chromium (Cr, 86 W / (m K)), tungsten (W, 197 W / (m K)), nickel (Ni, 85 W / (m K)) or mixtures or alloys, such as brass (120 W / (m K)), copper alloys with tin, zinc, nickel and / or lead or aluminum alloys with manganese, magnesium, copper, silicon and / or zinc. Suitable semimetals or semiconductor materials are silicon (Si, 163 W / (m K)), indium (In, 81.6 W / (m K)), and semiconductors such as the binary III-V semiconductors GaAs, InAs, and AlAs and / or the ternary semiconductors InGaAs or InAlAs, and mixtures thereof. Furthermore, the person skilled in the art knows how to determine the specific thermal conductivity for a suitable material or can obtain it from familiar tables and reference works.Thermal conductivity is a property of a material and describes how quickly the material can conduct heat. The higher the thermal conductivity, the faster the material cools down. In the SI system, thermal conductivity is measured in W / (m K) (watts per meter and Kelvin).

[0051] Furthermore, the expert knows how to determine the specific thermal conductivity for a suitable material or can obtain it from familiar tables and reference books. Thermal conductivity is a property of a material and describes how quickly the material can conduct heat. The higher the thermal conductivity, the faster the material cools down. In the SI system, thermal conductivity is measured in W / (m K) (watts per meter and Kelvin).

[0052] According to an advantageous embodiment, the substrate comprises or consists of materials such as metals, semiconductors, or alloys. Suitable metals include copper or aluminum, but also gold, silver, platinum, palladium, rhodium, titanium, tantalum, and zirconium, as are preferably used in the manufacture of jewelry or medical devices. A suitable semiconductor material is, for example, silicon. Although these materials are often difficult to process due to their high thermal conductivity, they exhibit good heat dissipation capabilities. Other possible materials include composites.

[0053] In a preferred embodiment of the present invention, suitable metals for applying a black marking are selected to ensure high contrast and clear visibility. Preferred metals include, for example, gold, silver, platinum, palladium, rhodium, titanium, tantalum, zirconium, copper, and aluminum. These metals are preferably used in the manufacture of jewelry items and medical devices or instruments. The choice of the respective metal is based on its specific properties and the intended field of application. Black marking on these metals not only enables an aesthetic improvement but also offers functional advantages such as improved visibility and differentiation, particularly for identification and labeling in medical and technical applications.The invention thus comprises the application of a black marking to the said metals in order to achieve clear visibility through the high contrast, in particular gloss contrast as defined herein, between the marked and the unmarked metal surface.

[0054] Metal alloys can also be selected for the application of a black mark, as defined herein, to optimize their applicability in various applications. In particular, stainless steel alloys such as 316L, nickel-titanium alloys (Nitinol), bronze alloys, brass alloys, white gold and rose gold alloys, and aluminum alloys are considered preferred materials. These metal alloys are particularly suitable for use in fields such as medical technology, jewelry manufacturing, art, and technical applications. Applying a black mark to these alloys not only serves to enhance aesthetics but also to provide functional identification, significantly improving the visibility and identifiability of the marked objects.Thus, the invention encompasses the application of high-contrast black markings, in particular with gloss factors as defined herein, to said alloys, taking into account the specific properties and fields of application of the individual alloys.

[0055] Other suitable materials include magnesium, titanium, and coatings or alloys based on them, as well as silicon carbide-based materials, ceramics, and preferably polymers and glass. An auxiliary layer is preferably applied to materials such as glass and polymers (as described herein), the material of which then forms the structure.

[0056] Specific glasses and ceramics can also be selected for the application of black markings to enhance their functionality and aesthetics in various applications. Preferred materials include, for example, float glass, borosilicate glass, colored glass, sapphire glass, and yttrium aluminum garnet (YAG). These materials are particularly suitable for use in areas such as the construction industry, laboratory equipment, art, watches and smartphones, and laser technology. Applying a black marking to these materials offers a variety of advantages, including improved visibility, permanent marking, and aesthetic design options. The invention thus encompasses the precise application of high-contrast black markings, in particular with gloss factors as defined herein, to the aforementioned glasses and ceramics, taking into account the respective properties and areas of application of the materials.Different types of plastics may also be used for applying black markings to maximize their benefits in various applications. These include, in particular, polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). These plastics are ideal for use in areas such as advertising, construction, packaging, and medical technology. Applying a black marking as defined herein, particularly while generating the gloss contrast values ​​defined herein, to these plastics enables a variety of advantages, including improved legibility, durable marking, and aesthetic design.The invention therefore comprises the precise application of high-contrast black markings, in particular with gloss factors as defined herein, to the said plastics, taking into account the specific properties and fields of application of the materials.

[0057] Within the scope of the present invention, various semiconductor materials, including silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), silicon carbide (SiC), and gallium nitride (GaN), are also selected for the application of black marks. These materials are widely used in the semiconductor industry, from microchips and radio-frequency components to power electronics and optical components. The application of a black mark as defined herein, in particular while generating the gloss contrast values ​​defined herein, to these semiconductors not only serves to improve aesthetics but also fulfills important functional purposes such as improved identification, tracking, and quality control. The invention therefore encompasses the precise application of high-contrast black marks to the aforementioned semiconductor materials, taking into account the specific properties and areas of application of the materials.

[0058] The material of the surface-structured substrate can also have a melting point of less than 1,400°C, preferably less than 1,200°C, particularly preferably less than 1,100°C. Those skilled in the art know how to determine the melting point or melting range for a suitable material, or they can obtain these values ​​from familiar tables and reference works. Structuring of such materials with a low melting point can also be advantageously achieved by using particularly short laser pulses, preferably of less than 500 ps (so-called ultrashort pulse lasers), particularly within ranges as defined herein. For other materials with higher melting points, such as stainless steel, pulse durations in the nanosecond (ns) range are sufficient and are significantly easier to implement.

[0059] With longer pulses starting from 1 ns, more heat, i.e. energy, is introduced into the material and a larger amount of material is melted, forming local wavefronts (at the maxima) that can overlap each other and thus lead to large structure heights.

[0060] With shorter pulses up to 1 ns, especially up to 500 ps, ​​the material is removed more quickly. Relevant effects here are cold ablation or material sputtering, so that pits are more likely to form and little to no melting occurs.

[0061] The substrate can also be flexible, such as a metal foil. It is particularly important that the surface irregularities are retained after a cooling process.

[0062] Preferably, the surface-structured substrate, in particular the laser-surface-structured substrate, has a second outer surface on the side facing away from the first outer surface. The second outer surface is formed from a structured and an unstructured region, wherein the structured region has a periodic dot and / or line structure. Thus, the advantageous effects and properties, in particular the improved heat transfer, can also be effective on the further, second outer surface. Especially when used within a component and / or within an electronic circuit, this can increase the heat dissipation coefficient and thus improve heat dissipation.

[0063] The structured region (black marking region) preferably has a ratio of the real surface to the projected surface of at least 120%, preferably 150%, particularly preferably 200%, in particular 250%. The "projected surface" is the projection surface onto the first outer surface without surface irregularities and is defined as the projection of the virtual surface or plane of a substrate (in the case of essentially flat substrates) onto the real surface without taking into account any surface irregularities applied or introduced. The projection surface can run along a plane, but it can also have curvatures. According to an advantageous embodiment, the substrate is flat, so that the projection surface is also flat. Alternatively, the substrate can also have a different shape; for example, it can be wire-shaped or spherical.In this case, the projection surface is the corresponding lateral surface of the substrate and / or the molding base body, which comprises or consists of the substrate to be structured and / or structured. With such molds, improved heat dissipation can advantageously be achieved, particularly with respect to fluids, preferably with respect to air.

[0064] Here, structures that enable the creation of a black marking area on a substrate are applied directly to the substrate. No additional material or particles are applied to the substrate. Instead, structuring is performed using a subtractive process, i.e., regions of the substrate surface are removed (see inverse cones, interference patterns). This advantageously eliminates the need to apply films or coatings to create a black marking area, which, compared to the structuring according to the invention, are susceptible to abrasion and thus wear out quickly. A black marking area as disclosed herein is characterized by robustness against wear and stress.

[0065] A further significant advantage of the present invention is that, after structuring the substrate, no additional material removal is required to achieve the disclosed properties of the black marking area. This means that, in contrast to other methods such as masking and lithography methods, no subsequent processes such as grinding, polishing, or etching, for example, chemical dry and / or wet etching or plasma etching, are necessary. This is particularly advantageous since conventional methods often use cover or auxiliary structures that must be removed after structuring. Such processes are typically associated with the loss of additional substrate material, in particular material of the unstructured area or global unstructured area.The invention avoids this additional material loss and thus reduces the overall material expenditure and the complexity of the manufacturing process. Furthermore, this procedure can also contribute to improving process efficiency and cost-effectiveness, as fewer work steps and materials are required. For example, the method according to the invention enables direct and precise structuring without the need for subsequent processing, which can be of great benefit, particularly in the case of sensitive or expensive substrates or thin layers. A structured substrate, as disclosed herein, is further characterized in that the substrate surface has a high level of purity in the unstructured region, as there are no impurities on it. Impurities are, for example, residues of sacrificial layers which are present during an etching process in the form of a masking layer, e.g.Photoresist, were applied. Conventional structured substrates, which were produced by an etching process such as plasma dry etching and / or chemical wet etching, require the substrate to be coated with a photoresist layer to protect the areas that are to remain unstructured. After the etching process, this layer must be removed, which can result in residues forming on the substrate surface and, on the other hand, interaction between the substrate surface and the cleaning solution. This changes the properties of the substrate surface in an undesirable way compared to an unstructured substrate surface. A structured substrate as disclosed herein is characterized in that the material properties of the substrate are retained in the unstructured areas.

[0066] According to a particularly preferred embodiment, a structured substrate as defined herein is characterized in that it has a structured region, wherein the structured region is divided into at least two subregions, wherein the respective subregions, for example a first and a second subregion, are characterized in that the structural features contained therein (e.g. the shape of the surface irregularities, the structural depth and / or the spacing of the surface irregularities from one another) differ from one another. The variation in the structural depth, structural period and / or shape of the surface irregularities between the subregions makes it possible to specifically optimize the substrate for specific applications. For example, one region could be configured for better light absorption and another for improved light reflection.The ability to gradually and adjustably change the gloss contrast and the color contrast opens up new design options, e.g. for decorative purposes or for the incorporation / application of security features. The at least two partial regions can be arranged so as to overlap (lie one above the other), adjacent to (adjacent to) one another and / or at a distance from one another. Preferably, the at least two partial regions are arranged so as to overlap and / or adjacent to one another. In particular, the structure depth and / or the structure period of the respective structure features are different. This advantageously produces a structuring which is characterized by a gradual, adjustable change in the contrast, in particular the gloss contrast and / or the color contrast. Particularly preferably, the structure period and the shape of the structure features of the two partial regions are identical. Conventionally structured substrates, which e.g.are created by an etching process, are characterized by a homogeneous structure depth. Multiple etching processes to modify the structure depth in specific areas are difficult due to the requirement of a sacrificial layer. Due to the presence of pre-existing etched flanks, a homogeneous coating of a substrate that already has a structure with the sacrificial layer is difficult to achieve. This creates uncovered areas that are then attacked by a further etching process. Thus, homogeneous structuring is not guaranteed. A gradual, adjustable change in contrast, particularly in gloss contrast and / or color contrast, cannot be ensured.

[0067] Preferably, the at least two sub-regions are each formed independently of one another by a first periodic structure with a first interference period (pi) in the micro- or sub-micro range (e.g. the first sub-region) and by a second periodic structure with a second interference period (p2) in the micro- or sub-micro range (e.g. the second sub-region). The first and the second interference periods can be identical or different from one another. Preferably, the first periodic structure with a first interference period (pi) in the micro- or sub-micro range is produced by applying a first interference pixel once or multiple times, congruently and / or offset from one another, and the second periodic structure with a second interference period (p2) in the micro- or sub-micro range is produced by applying a second interference pixel once or multiple times, congruently and / or offset from one another.By applying an interference pixel multiple times in a congruent manner (multiple irradiation as defined herein), the structure depth can be adjusted in the corresponding partial area and / or a quasi-periodic line structure superimposed on the periodic structure, in particular a periodic dot structure, can be formed as a wave structure through self-organization processes.

[0068] For the purposes of the present invention, “adjacent subregions” refers to an arrangement in which at least two structured subregions of the surface-structured substrate are arranged in a stacked configuration. One subregion lies directly above another, with the two subregions occupying at least partially the same physical space and / or the same physical area (projected surface). This superimposed arrangement enables multidimensional structuring of the substrate, with each subregion being able to have different properties or structural features. For the purposes of the present invention, “adjacent subregions” refers to an arrangement in which two or more structured subregions of the substrate are arranged side by side with and / or without overlapping subregions.These sub-areas are directly adjacent to one another and occupy, entirely or at least partially, a different physical space and / or a different physical surface (projected surface), with their border forming a common boundary line or interface. This arrangement enables the creation of structures in which the transitions between the different sub-areas are clearly defined, thus allowing precise control of the contrast and structural properties at the boundaries.

[0069] The invention defines "spaced-apart partial regions" as an arrangement in which two or more structured partial regions of the substrate are arranged or applied at a significant spatial distance from one another on the surface of the surface-structured substrate. Between these partial regions there is either an unstructured region of the substrate or a gap. This arrangement is particularly advantageous for creating isolated structured regions, each with specific properties or functions, without direct interaction or influence from neighboring structured regions.

[0070] For the purposes of the present invention, a surface of a substrate with a black marking region preferably has a structured region. Preferably, at least 25% of the total area of ​​the substrate's surface is assigned to the structured region, particularly preferably at least 50%, and most preferably at least 75%. In various embodiments, the surface of a substrate with a black marking region has a structured region, wherein the proportion of the surface assigned to the structured region lies in a numerical range obtained by combining any two of the following endpoint values: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99%.

[0071] A structured region on the surface of a substrate is preferably characterized in that a regularly arranged structure (as defined herein) with a mean structure period is arranged within the structured region. A mean structure period refers in particular to the distance between two generated structural features, for example, dot structures and / or line or wave structures, with dimensions in the micrometer and / or submicrometer range. Within the meaning of the invention, a mean structure period also includes the distance between two structural features fluctuating around a statistical mean and / or the periodicity being broken by individual defects in the generated structural features.In this embodiment, the unstructured regions of the surface of the substrate which are located between two structural features arranged at a distance of a mean structural period, in particular dot structures and / or line or wave structures, are also regarded as being assigned to the structured region.

[0072] In this embodiment, the substrate has a globally unstructured region. The globally unstructured region is characterized by the fact that this region contains no structural features with dimensions in the micrometer and / or submicrometer range that are spaced apart by an average structural period. Advantageously, the black marking effect thus only occurs in the structured regions. This allows a pattern and / or image to be created on the surface of the substrate, which results from a black and a non-black region. Depending on the selected process parameters, a high-contrast pattern can be created.

[0073] In the context of the invention, a high contrast also refers to the gloss contrast between a structured area on the surface of a substrate and a non-structured area, in particular a global unstructured area. In general, the gloss contrast GC can be defined as

[0074] GC = \G A -G B \ max(G A ,Gß) where GA and GB each indicate the gloss factor of an area of ​​the substrate.

[0075] For example, the gloss factor of untreated substrates consisting of a metal is close to 100. For example, the gloss factor for stainless steel is close to 100, the gloss factor of gold is close to 100, the gloss factor of silver is close to 100, the gloss factor of platinum is close to 100, the gloss factor of white gold and rose gold is over 80, the gloss factor of brass is over 80, the gloss factor of copper is over 80, the gloss factor of aluminum is between 80 and 90, the gloss factor for titanium is between 60 and 80, the gloss factor of palladium is close to 100, the gloss factor of nickel-silver is between 60 and 80, the gloss factor of medical stainless steel alloys is up to 100, the gloss factor of surgical steel is over 80, the gloss factor of rhodium is close to 100, the gloss factor of tantalum is over 80, the gloss factor of zirconium is over 80, the gloss factor of bronze is between 60 and 80, the Gloss factor of polished nickel-titanium (Nitinol) at 60 to 80, the gloss factor of float glass close to 100,The gloss factor of borosilicate glass is close to 100, the gloss factor of colored glass is over 80, the gloss factor of sapphire is close to 100, the gloss factor of yttrium aluminum garnet (YAG) is over 80, the gloss factor of polymethyl methacrylate (PMMA), also known as acrylic or Plexiglas, is between 90 and 95, the gloss factor of polycarbonate (PC) is between 80 and 90, the gloss factor of polyethylene terephthalate (PET) is between 60 and 80, and the gloss factor of polyvinyl chloride (PVC) is between 50 and 60.

[0076] In one embodiment of the invention, the gloss contrast between the surface of the originally unstructured region of a substrate and the surface with the structured region is greater than 0.85, preferably greater than 0.9, particularly preferably greater than 0.95, very particularly preferably greater than 0.99, further preferably 1.00 (according to rounding convention). The gloss contrast is particularly preferably in a numerical range that is limited downwards by one of the following endpoint values: 0.85, 0.87, 0.88, 0.93, 0.94, 0.95, 0.97, 0.98, 0.99, 1.00 (according to rounding convention). The technical advantages of this embodiment lie in the possibility of specifically creating optical effects by selectively structuring the surface.The high gloss contrast enables a clear visual separation between the structured and / or unstructured areas, which is important for aesthetic design purposes, such as decorative surfaces or marking technology. Partial structuring also allows specific functional properties, such as improved grip or modified reflective properties, to be restricted to specific areas of the substrate, opening up new application possibilities. This type of structuring can be used, for example, in the production of security features, in optical marking, or in user interaction in various products.

[0077] In a preferred embodiment of the invention, the surface of the substrate is structured over its entire area. In this embodiment, the structured region of the substrate extends over the entire substrate surface. This embodiment leads to a distinct matting of the surface. The matting is characterized in that the gloss contrast between the surface of the original, non-structured substrate is preferably greater than 0.85, preferably greater than 0.9, particularly preferably greater than 0.95, most particularly preferably greater than 0.99, and further preferably 1.00. Particularly preferably, the gloss contrast lies in a numerical range that is limited downwards by one of the following endpoint values: 0.85, 0.87, 0.88, 0.93, 0.94, 0.95, 0.97, 0.98, 0.99, 1.00 (according to rounding conventions).The technical advantage of this matting lies in the improved grip of the substrate, which is particularly beneficial for applications that require user interaction. Another advantage of full-surface structuring is the uniform light scattering, which reduces glare and improves the readability of the information displayed on the substrate. Furthermore, there is an aesthetic advantage in the significant reduction in gloss, giving the surface a high-quality and aesthetically pleasing appearance. In addition, the structured surface offers an increased surface area that can be used for various functional effects, such as improved thermal conductivity, and / or coatings, such as hydrophobic or antimicrobial layers, thereby expanding the functionality of the substrate.

[0078] In a further embodiment of the invention, the surface of the substrate has a structured and a global unstructured region. In this embodiment of the invention, a structured region borders on a global unstructured region, wherein the global unstructured region has a gloss factor that is higher than the gloss factor of the structured region. Thus, a high gloss contrast can be generated between the structured region and the unstructured region, in particular at their boundary line (i.e., the immediate transition between the two regions). The gloss contrast preferably lies in a numerical range that is limited downwards by one of the following endpoint values: 0.85, 0.87, 0.88, 0.93, 0.94, 0.95, 0.97, 0.98, 0.99, 1.00 (according to rounding conventions). The technical advantages of this embodiment lie in the possibility of specifically generating optical effects by selectively structuring the surface.The high gloss contrast enables a clear visual separation between the structured and / or unstructured areas, which is important for aesthetic design purposes, such as decorative surfaces or marking technology. Partial structuring also allows specific functional properties, such as improved grip or modified reflective properties, to be restricted to specific areas of the substrate, opening up new application possibilities. This type of structuring can be used, for example, in the production of security features, in optical marking, or in user interaction in various products.

[0079] In a further embodiment of the invention, the surface of the substrate has a structured and a globally unstructured region. In this embodiment of the invention, a structured region borders a globally unstructured region, wherein the structured region is characterized in that the structural depths of the generated structural features vary within the structured region. In particular, within the structured region, at least one region of high structural depth borders at least one region of lower structural depth, wherein the gloss factor differs between the two regions. Preferably, a gradual transition between different gloss factors can be generated in this way.

[0080] It may be provided that, in addition to the black marking area, the surface of the structured substrate has one or more other laser-structured areas, for example, areas with improved anti-glare properties. The different areas may overlap.

[0081] Transparent substrate

[0082] According to one possible embodiment, the substrate consists of a transparent material. A material or substrate is transparent within the meaning of the present invention if it has a high transmittance for at least a partial range of the spectrum of electromagnetic radiation between 1 nm and 10 nm, preferably for light that is visible to the human eye or light in the infrared or ultraviolet radiation range. Such partial ranges are, for example, electromagnetic radiation in the range of ultraviolet (UV) light from 100 nm to 380 nm, in particular UV-A from 315 nm to 380 nm or UV-B from 280 nm to 315 nm or UV-C from 100 nm to 280 nm, visible light from 380 nm to 780 nm or in a range that also includes infrared light, from 780 nm to 5.000 nm or in a range of infrared light (heat radiation) or in a range of microwave radiation, in particular radar beams in the wavelength range from 1 mm to 10 m, or else another sub-range which is adapted according to the desired application, in particular to the wavelength of the laser source. Such a sub-range preferably has a width of at least 10% or 50% of the wavelength which forms the lower limit of the sub-range. A high permeability in a sub-range within the meaning of the invention is a transmittance of at least 50% or preferably at least 70% or particularly preferably at least 80% or at least 90% for each wavelength in the sub-range, i.e. for the entire spectrum in the sub-range.In contrast, a substrate is referred to as partially transparent if it has at least a certain degree of transmittance, preferably at least 20% for each wavelength in the sub-range, i.e., for the entire spectrum in a sub-range described herein. Those skilled in the art know how to determine the transparency and / or light transmittance for a suitable material or can obtain these values ​​from familiar tables and reference works.

[0083] Preferably, the substrate is transparent, i.e., in a sub-range of the electromagnetic spectrum, preferably in the range of visible light or near-infrared light or the UV range, in particular IIV-A and / or UV-B and / or UV-C, it has a transmittance of at least 50%, preferably at least 70%, particularly preferably at least 80%, at least 90% for each wavelength in the sub-range.

[0084] A transparent substrate can also be defined as one that selectively exhibits high transmittance for certain wavelength ranges in the visible light range. For example, the substrate has high transmittance for electromagnetic radiation with wavelengths in the range from 500 nm to 800 nm. The transmittance can vary across the transmitted wavelength range, e.g., it can be no less than 70% for wavelengths in the range from 380 nm to 500 nm, and no less than 90% in the range from 500 nm to 750 nm. For example, the substrate transmits radiation with wavelengths from 380 nm to 780 nm. It exhibits particularly high transmittance, e.g., a transmittance of 90%, at wavelengths from 450 nm to 690 nm; the transmittance at wavelengths below and above this range is, for example, 70%.

[0085] A transparent material, in the sense of the present invention, includes transparent materials, in particular glass (e.g., borosilicate glasses, quartz glasses, alkali-alkaline earth silicate glasses (e.g., soda-lime glass), aluminosilicate glasses, metallic glasses), but also solid polymers (e.g., polycarbonates such as Makrolon® and Apec®; polycarbonate blends such as Makroblend® and Bayblen®; polymethyl methacrylate such as Plexiglas®; polyester; polyethylene terephthalate, polypropylene, polyethylene) as well as transparent ceramics (e.g., spinel ceramics such as Mg-Al spinel, ALON, aluminum oxide, yttrium aluminum garnet, yttrium oxide, or zirconium oxide) or mixtures thereof. Polycarbonates include homopolycarbonates, copolycarbonates, and thermoplastic polyestercarbonates.

[0086] A transparent material, in the sense of the present invention, includes transparent materials, in particular transparent ceramics (e.g., spinel ceramics such as Mg-Al spinel, ALON, aluminum oxide, yttrium aluminum garnet, yttrium oxide, or zirconium oxide) or mixtures thereof. Polycarbonates include homopolycarbonates, copolycarbonates, and thermoplastic polyestercarbonates.

[0087] To create a black marking area on a first outer surface of a transparent material, the structured area preferably consists of a different material, which rests on the transparent material as a cover layer. The surface irregularities on the surface of the transparent material are preferably studs or groove-like elevations formed from a different material.

[0088] Surface irregularities

[0089] Within the meaning of the invention, the surface irregularities can be formed as point-shaped surface irregularities or as linear surface irregularities. The point-shaped surface irregularities can be formed as pegs or as inverse pegs. The linear surface irregularities can be formed as groove-shaped depressions or as groove-shaped elevations. In particular, different interference pixels with different surface irregularities can also be arranged superimposed, so that different dimensions and / or different types of surface irregularities can be arranged on a surface-structured substrate, in particular within a black marking area. The dimensions of the surface irregularities can be adjusted by different process parameters when produced by laser interference structuring.In the sense of the invention, a superposition of different types of surface irregularities means a superposition of both point and line structures.

[0090] According to an advantageous embodiment, the side surfaces of the surface irregularities of the first periodic structure, preferably all surface irregularities, have a smooth surface. This distinguishes these structures significantly from surface irregularities produced by etching. Even when using masks, the side surfaces or lateral surfaces of the surface irregularities cannot be produced as smoothly as with laser interference structuring. This advantageously allows for the creation of defined structures and optimized properties.

[0091] A smooth side surface (lateral surface) of the surface irregularities, i.e. the pegs or inverse pegs or groove-shaped depressions or groove-shaped elevations, is preferably achieved by irradiating the individual surface irregularities during structuring by means of laser structure application methods, in particular by means of direct laser interference structuring, no more than four times, in particular no more than three times, particularly preferably no more than twice, and most preferably only once. Each interference pixel is preferably generated by single irradiation. For the purposes of the invention, a side surface of a structure, e.g. a peg or inverse peg or groove-shaped depressions or groove-shaped elevations, is considered smooth if the mean roughness value (R a) according to DIN EN ISO 4287:2010 is less than 200 nm, preferably less than 50 nm, particularly preferably less than 20 nm, most preferably less than 5 nm.

[0092] A smooth side surface, also known as the lateral surface, of the surface irregularity, i.e., the pegs and / or inverse pegs or groove-like depressions or groove-like elevations, has the advantage over a rough surface that, especially when electromagnetic radiation is irradiated, it is not diffusely scattered back from the surface. The side surface of the depressions thus serves, for example, in the adjustment of desired optical properties.

[0093] For example, a trapping effect occurring within the pegs or inverse pegs or groove-shaped depressions or groove-shaped elevations can be improved and thus the transmittance of light through this interface can be increased, since the side surface serves as a quasi-homogeneous mirror surface which reflects the portion of reflected incident electromagnetic radiation within the surface irregularities, in particular the inverse pegs, up to the saddle point, wherein at each further reflection point within the lateral surface a portion of (remaining) electromagnetic radiation is coupled into the substrate, the first outer surface of which is formed from such a structured and an unstructured area.

[0094] Point-like structure / interference pattern

[0095] According to an advantageous embodiment of the surface-structured substrate, the first interference pixel has a periodic lattice of at least three cones or inverse cones. This forms a first periodic dot structure. The surface irregularities, also referred to herein as structural features, are thus cones and / or inverse cones. The two-dimensional changes in the surface properties present here lead to an efficient enlargement of the surface and a resulting improved heat transfer. This allows a greater amount of heat to be conducted through the black marking area.

[0096] The term “inverse cone” in the sense of this invention refers to structures with a circular, elliptical, triangular or essentially rectangular base area, in particular with a circular base area, which taper pyramidally or conically into the substrate in the vertical direction and have a pyramidal tip or pointed or rounded conical tip, in particular a rounded conical tip, at their saddle point. The inverse cones are formed during the structuring process, i.e. when a laser pulse strikes the substrate to be structured as a result of a region of high intensity impinging on it, the regions between the inverse cones on or within the substrate ideally remaining essentially unstructured due to destructive interference whose intensity is zero. Consequently, by focusing the laser (partial) beams on orWithin the substrate, the negative of what determines the intensity distribution is formed. The described shape of the inverse cones refers to point structures arranged on the surface of the substrate. An arrangement of the point structures in or along a plane within the volume leads to a more symmetrical shape. For the purposes of the invention, the point structures generated within a volume by means of laser interference structuring are also referred to as inverse cones.

[0097] In a preferred embodiment, the inverse cones are preferably generated during the structuring process by means of laser structure application methods, in particular direct laser interference structuring, i.e. they are formed upon impact of a laser pulse as a result of the impact of a high-intensity region on the substrate to be structured, wherein the regions between the inverse cones on or within the substrate ideally remain essentially unstructured due to destructive interference whose intensity is zero, in particular below a material-dependent intensity threshold. Consequently, by focusing the (partial) laser beams on or within the substrate, the negative of what specifies the intensity distribution is formed. The described shape of the inverse cones refers to point structures arranged on the surface of the substrate.An arrangement of the dot structures in or along a plane within the volume results in a more symmetrical shape, i.e., more like an ellipsoid. For the purposes of the invention, the dot structures generated within a volume by laser interference structuring are also referred to as inverse cones.

[0098] Inverse cones with an elliptical base surface can be created in a structuring process using laser structure application methods, for example by inclining the substrate in relation to the angle of incidence of the focused laser beam(s).

[0099] For the purposes of this invention, "pins" refer to structures with a circular, elliptical, triangular, or substantially rectangular base, in particular with a circular base, which protrude conically from the substrate in the vertical direction and have a rounded cone tip or a truncated cone, in particular a rounded cone tip, at their saddle point. Pins can be applied to or embedded in a surface by applying a negative mold having inverse pins. Imprint lithography, e.g., nanoimprint lithography (as defined herein), is suitable for this purpose.

[0100] The periodic dot structures defined herein, which are preferably formed from cones and / or inverse cones (according to the orientation relative to an outer surface of a substrate or a cover layer, or in the direction of the stacking or coating direction), have the advantage over (periodic) line or wave structures that the individual depressions or elevations span a lateral surface that preferably extends radially across the cone cross-section (diameter of the base surface of the cone or inverse cone) to the saddle point. This enables the optical effects defined herein to be adjusted independently of the spatial orientation of the respective surface or interface.

[0101] In optics, a pixel is generally understood to be an image point, defined as a finite unit created by the unification of light emanating from an object point by means of an optical system (https: / / de.wikipedia.org / wiki / Optische_Bildung). The term "pixel" is an abbreviation of "picture element"; a term that has been used with a fixed meaning in various US patents since 1911. The term "pixel" became established in technical literature in 1965 (https: / / de.wikipedia.org / wiki / Pixel) and is also used in the context of raster graphics, for example, in relation to image displays such as LCDs or OLEDs. It refers to a raster point within an image, where the pixels within a raster are arranged such that the distances between one pixel and the next are constant.A pixel is particularly characterized by the fact that it has a defined information content that varies or can be varied between individual pixels within a grid.

[0102] The term “interference pixel” or “DLIP pixel” is established in the specialist literature from the field of surface structuring using direct laser interference structuring (e.g. “Development of a general model for direct laser interference patterning of polymers”, Alamri, Lasagni, Optics Express, Vol. 25, Issue 9; 2017; “How to Tailor Structural Colors for Extended Visibility and White Light Generation Employing Direct Laser Interference Patterning”, Storm et al., Macro-Molecular Chemistry and Physics, Vol. 220 Issue 13, 7.2019; “Scanner-Based Direct Laser Interference Patterning on Stainless Steel”, Madelung et al., Advanced Engineering Materials, VOL 23, Issue 6, 6.2021 ; “Direct laser interference patterning of stainless steel by ultrashort pulses for antibacterial surfaces”, Peter et al., Optics and Laser Technology 123, 2020) and refers to a spatial region, preferably on the surface of a substrate, preferably a flat and / or transparent substrate, in which laser (partial) beams directed onto the surface interfere constructively and destructively with each other, thus forming a pattern of periodically arranged intensity minima and intensity maxima. The region is preferably spatially limited in such a way that it encompasses an area that is significantly smaller than the surface of the substrate.

[0103] The term “interference pixel”, for example first, second, third and / or further interference pixel, refers in the sense of the present invention to a periodic pattern or grid of at least three cones or inverse cones, preferably of at least seven cones or inverse cones, very particularly preferably at least 19 cones or inverse cones on the surface of a substrate, which are formed within an interference pixel (cf. Fig. 15). An interference pixel which is formed from cones or inverse cones is preferably characterized in that the cones or inverse cones are repetitively aligned to one another in such a way that, when there are three cones or inverse cones, these are aligned to one another in such a way that their vertices (in the case of cones, their height centers or, in the case of inverse cones, their centers of the depressions) are at the same distance from one another (so-called

[0104] Interference period). If there are seven cones or inverse cones, these are aligned with each other in such a way that one cone or inverse cone is located centrally in the grid, whereas the six remaining cones or inverse cones are arranged around the center in such a way that each of the vertices (in the case of cones, their height centers or, in the case of inverse cones, their centers of the depressions) of the six remaining cones or inverse cones is at the same distance from the cone or inverse cone in the center and from at least two other of its neighboring cones or inverse cones (so-called interference period).

[0105] Preferably, the periodic pattern or grating of the interference pixel, in particular comprising inverse cones, is produced by mechanical methods, laser structure application methods, and / or by chemical (post-)treatment, in particular by direct laser interference structuring. In the case of direct laser interference structuring, the periodic pattern or grating is preferably generated by superimposing at least three, particularly preferably at least four, laser (partial) beams by focusing (bundling) these laser (partial) beams onto the surface or into the interior of the substrate, whereby the partial beams interfere constructively and destructively on the surface or in the interior of the substrate.

[0106] The use of laser structure application methods, in particular direct laser interference structuring for the direct production or indirect production (e.g. in the case of imprint lithography, in particular nanoimprint lithography) for producing structured and unstructured regions on the surface of a substrate has the advantage that the cones or inverse cones of a periodic dot structure within a type of interference pixel have identical or almost identical dimensions. Preferably, the coefficient of variation, i.e. the value resulting from the quotient of the standard deviation and the average value, of the cone cross-section (diameter of the base area of ​​the cone or inverse cone) is max. 15.0% or less, more preferably max. 10.0% or less, even more preferably max. 5.0% or less, in particular max. 2.5% or less, even more preferably max. 1.0% or less.This allows for the production of studs or inverse studs that are virtually identical in shape. This also allows for better detection of the substrate structured according to the invention compared to conventional methods for structuring / coating substrates (e.g., etching, particle blasting, polymer coating). Particularly in the case of etching processes, deviations in the structural features can be detected in the edge regions of a substrate structured in this way. A coefficient of variation as specified here cannot be generated by an etching process.

[0107] Line structure or line-shaped structure

[0108] According to one possible embodiment, the first periodic structure is formed as a first periodic line structure, which is formed from at least three, preferably at least 5, more preferably at least 7, parallel groove-shaped depressions or groove-shaped elevations. The groove-shaped depressions or groove-shaped elevations are arranged such that the distance from a groove-shaped depression or a groove-shaped elevation to an adjacent groove-shaped depression or groove-shaped elevation within the periodic line structure is always identical. The individual groove-shaped depressions or groove-shaped elevations within the first periodic line structure are thus arranged equidistantly. This forms a first periodic line structure. The surface irregularities, also referred to herein as structural features, are therefore groove-shaped depressions and / or groove-shaped elevations.Such structures require only two superimposed laser beams. Therefore, they can be produced quickly and economically, thus improving efficiency. The resulting period of the periodic line structure, i.e., the structural period, is referred to in the invention as the interference period (p. n). The interference period is the shortest distance from a point on a grooved depression or a grooved elevation to an analogous point on the adjacent grooved depression or grooved elevation within the periodic line structure. For example, the interference period corresponds to the shortest path between two center lines or deepest lines on a grooved depression or highest lines on a grooved elevation. The deepest lines on a grooved depression are the center lines where the most material has been removed. Depth here applies relative to the corresponding surface, particularly relative to the unstructured area of ​​the surface.

[0109] The same applies analogously to groove-shaped elevations, with the deepest line being the highest line. In the context of the invention, groove-shaped elevations are structures that rise from the surface in the same shape as a groove or groove-shaped depression. One way to create such groove-shaped elevations is to apply groove-shaped depressions to a negative mold and then transfer this structure to the cover layer.

[0110] Analogous to the point structures, i.e., the cones or inverse cones, the groove-shaped depressions and the groove-shaped elevations can also be arranged within an interference pixel. An interference pixel has at least three, preferably at least five, and more preferably at least seven parallel, equidistantly arranged groove-shaped depressions or groove-shaped elevations.

[0111] Repetitively arranged interference pixels can form either a periodic or a non-periodic global structure. The degrees of freedom are the selected interference period, the direction of the first dimension along which the groove-shaped depressions or groove-shaped elevations extend the most, the structure depth, and the spacing or offset of the individual interference pixels. The global structure forms the structured area.

[0112] The groove-shaped depressions are preferably created using a mechanical process, a laser pattern application process, and / or chemical (post-)treatment. The structure, in particular its interference period, generally depends on the structuring of a mask, the negative of the desired periodic dot structure on a mold, or the wavelength of the interfering laser beams, the angle of incidence of the interfering laser beams, and the number of interfering laser beams.

[0113] In a preferred embodiment, the groove-shaped depressions are preferably created during the structuring process using laser structure application methods, in particular direct laser interference structuring, i.e., they are formed upon the impact of a laser pulse as a result of the impact of a high-intensity region on the substrate to be structured. The regions between the groove-shaped depressions on or within the substrate ideally remain substantially unstructured due to destructive interference whose intensity is below a material-dependent intensity threshold. Consequently, by focusing the laser (partial) beams on or within the substrate, the negative of what the intensity distribution specifies is formed.

[0114] In the case of producing the depressions, in particular the groove-shaped depressions, by direct laser interference structuring, the periodic structure is preferably produced by superimposing at least two, preferably exactly two, laser (partial) beams as a result of focusing (bundling) these laser (partial) beams onto the surface or into the interior of the substrate, whereby the partial beams interfere constructively and destructively on the surface or in the interior of the substrate.

[0115] The use of laser structure application methods, in particular direct laser interference structuring for the direct production or indirect production (e.g. in the case of imprint lithography, in particular nanoimprint lithography) for producing structured and unstructured regions on the surface of a substrate has the advantage that the depressions, in particular the groove-shaped depressions or the groove-shaped elevations, of a periodic dot structure within a type of periodic structure, in particular a periodic line structure, have identical or almost identical dimensions. Preferably, the coefficient of variation, i.e. the value resulting from the quotient of the standard deviation and the average value, of the groove width (width of the groove-shaped depression or width of the groove-shaped elevation, determined on the surface, i.e. preferably at the boundary to the unstructured region) is max.15.0% or less, more preferably max. 10.0% or less, even more preferably max. 5.0% or less, in particular max. 2.5% or less, even more preferably max. 1.0% or less. Thus, groove-shaped depressions or groove-shaped elevations can be created that are almost identical to one another in shape. This also allows for better detectability of the substrate structured according to the invention compared to conventional methods for structuring / coating substrates (e.g., etching, particle blasting, polymer coating).

[0116] Rasterize

[0117] In a preferred embodiment, by moving the substrate, in particular the surface-structured substrate, in relation to the focusing point, which generates the interference pixel with a periodic point structure or a periodic line structure, in combination with pulsed laser (partial) beams, a planar, optionally homogeneous and periodic, point and / or line structure can be generated on the surface of a substrate, preferably a planar one.

[0118] As an alternative to moving the substrate relative to the focus point, the focus point can also be moved over the sample or substrate (e.g. using scanner-based methods).

[0119] Displacing the substrate to be structured, preferably a flat substrate, in the laser beam can be comparatively complex and slow due to the relatively large masses moved. It is therefore advantageous to keep the substrate, preferably a flat substrate, stationary during processing and to achieve the flat structuring of the substrate by focusing the partial beams onto the surface of the substrate by manipulating the laser partial beams with optical elements (focusing mirrors or galvo mirrors (laser scanners)) in the beam direction. Since the masses moved are relatively small, this can be achieved with far less effort and much faster. The substrate is preferably arranged in a stationary manner during the process.It is also possible to switch between moving the substrate and guiding the focus point over the substrate, which allows large substrates, for example larger than 200 mm x 200 mm, to be structured efficiently yet in a defined and reproducible manner.

[0120] Global structure, especially global point structure

[0121] Advantageously, the individual pixels of a type of interference pixel, e.g., a first interference pixel, a second interference pixel, and / or a further interference pixel, which are arranged adjacently and repetitively offset from one another, can optionally form a periodic or a non-periodic global point and / or global line structure globally (i.e., over the extent of the plane to be structured). A fully periodic global point and / or global line structure is generated or exists when the preceding pixel and the following pixel of a type of interference pixel are each offset by a whole multiple (e.g., 2, 3, 4, 5) of the interference period (p n ) are shifted from each other in one spatial direction. This results in a fully periodic pattern over the extent of the plane to be structured, the period of which corresponds to the interference period (p n ) corresponds.

[0122] A quasi-periodic global point and / or global line structure is created or exists when the preceding pixel and the following pixel of a type of interference pixel are each offset by an equal multiple (e.g. 0.5; 1.3; 2.6) of the interference period (p n ) are shifted relative to one another in a spatial direction. In contrast, a non-periodic global point and / or global line structure is created or exists when the interference period of the subsequent pixel is varied relative to the adjacent, preceding pixel and / or when adjacent, repetitively offset pixels are rotated, e.g., applied in a successively rotated manner.

[0123] For the purposes of the invention, a global structure describes a structure forming the structured region consisting of any surface irregularities, preferably inverse pegs and / or groove-shaped depressions, or according to a further preferred embodiment, pegs and / or groove-shaped elevations. Such a global structure can be fully periodic, whereby this preferably allows only one type of surface irregularity, or quasi-periodic or non-periodic. The type of periodicity has a major influence on the desired surface properties, particularly the optical properties.

[0124] According to an advantageous embodiment, deeper structure depths can be created by repeatedly irradiating existing surface irregularities, such as groove-shaped depressions. In line structures, the structure depths become deeper, i.e., larger, the stronger the pixel-to-pixel overlap, in particular the pulse-to-pulse overlap, i.e., the overlap of the interference pixels, in the line direction. Preferably, an overlap occurs transversely to the line direction, which also leads to deeper structures. Since the structure depth has a strong influence on the ratio of the surface area to the projected surface, a high structure depth can lead to an increased heat transfer coefficient. This improves the heat transfer properties.

[0125] According to an advantageous embodiment of the surface-structured substrate, the black marking region, in particular the structured region, further comprises a second periodic structure with a second interference period (p2) in the micro- or submicro-range, which is formed as a periodic dot structure or as a periodic line structure.

[0126] Preferably, the structured region of the surface of the substrate further comprises a second periodic dot structure, wherein the second periodic structure is formed from at least one second interference pixel (11) with a second interference period (p2). To form a second periodic dot structure, the second interference pixel (11) comprises a periodic grid of at least three cones or inverse cones with a second interference period (p2). The structured region, i.e., the global structure, is thus formed from a superposition of a first periodic dot or line structure and at least one second periodic dot structure.

[0127] Optionally, the structured region has a second periodic line structure with a second interference period in the micrometer or submicrometer range. Preferably, the second periodic line structure is formed from at least one second interference pixel with a second interference period (p2). To form a second periodic line structure, the second interference pixel has at least three parallel groove-shaped depressions or groove-shaped elevations. This then results in a global structure that is a superposition of a first periodic dot or line structure and a second periodic line structure.

[0128] According to an advantageous embodiment, the structured region has two superimposed line structures which differ in direction. Thus, a first interference pixel consisting of groove-shaped depressions and / or elevations and a second interference pixel consisting of groove-shaped depressions and / or elevations are superimposed. The first interference period and the second interference period can be identical or different. Preferably, a plurality of first and a plurality of second interference pixels with linear surface irregularities are superimposed in such a way that the linear surface irregularities of the first interference pixels all point in one direction and that the linear surface irregularities of the second interference pixels all point in one direction, i.e. enclose a maximum angle of 5°, preferably 1°.The repetitively arranged first interference pixels and also the second interference pixels are therefore not or hardly rotated relative to each other.

[0129] The linear surface irregularities of the first interference pixels and the linear surface irregularities of the second interference pixels are preferably arranged orthogonally to one another and preferably enclose an angle of 30° to 150°, preferably 45° to 135°, particularly preferably 60° to 120°, most preferably 80° to 100°, and especially 85° to 95°. This allows two-dimensional changes to the surface to be created. This allows the black marking to be further improved.

[0130] Since the line structures that run in different directions create more isotropic structures, the optical impression is more homogeneous, especially over a larger viewing area.

[0131] Preferably, two-dimensional changes in the surface, i.e., two-dimensional surface irregularities, are present in the black marking area. This includes both the dot structures, i.e., the cones or inverse cones, as well as the above-described superimposed line structures enclosing an angle in the range of 30° to 150°. The two-dimensional change in the surface can achieve a good surface roughness, i.e., a good ratio of the real surface to the projected surface of at least 120%, preferably more, in particular at least 150%, preferably at least 250%, particularly preferably at least 300%, most particularly preferably at least 350%.

[0132] The structural depth of the first periodic structure, i.e., the depth or height of the surface irregularities relative to the unstructured surface on the first outer surface, is preferably in the range of 0.3 pm to 60 pm, more preferably in the range of 0.5 pm to 40 pm. To achieve such structural depths, there is preferably an overlap of the interference pixels. Structural depths of more than 1 pm have proven particularly advantageous. Top layer

[0133] The surface-structured substrate has or consists of at least one cover layer.

[0134] For the purposes of the invention, a "cover layer" is a layer of the substrate which, when used as intended, is designed to seal the substrate from the environment. The cover layer delimits the substrate in at least one spatial direction and preferably represents the substrate's closure directly from the medium surrounding the substrate, preferably air or water.

[0135] A cover layer has a first outer surface that seals the substrate from the outside, i.e., from the environment, during intended use. The first outer surface of the cover layer defines the interface between the cover layer and the environment. For example, the environment surrounding the substrate is air.

[0136] The cover layer has a second outer surface, which is arranged on the side of the cover layer facing away from the first outer surface. The second outer surface can form a seal between the component and the environment or be designed as an interface to a base layer, preferably made of a carrier material, such as a molding base body.

[0137] For the purposes of the invention, the normal of the first outer surface pointing to the environment is referred to as the stacking direction or the coating direction.

[0138] According to an advantageous embodiment, the cover layer is a coating that is applied to the base layer in the stacking direction. The base layer is then coated with the cover layer.

[0139] The cover layer can also be formed as a layer stack comprising a plurality of partial cover layers, wherein the depressions according to the invention of the structured region of the first outer surface of the cover layer penetrate through or at least extend into a plurality of the partial cover layers.

[0140] According to a preferred embodiment, the cover layer forms the substrate. The cover layer, which, during intended use, directly separates the surface-structured substrate from the environment, can comprise or be formed from a metal, preferably copper and / or aluminum, an alloy and / or a semiconductor, preferably silicon. This cover layer preferably has the first outer surface with a structured and an unstructured region.

[0141] A typical example of an alloy is steel or cast steel, e.g. stainless steels according to EN 10020, such as alloyed steels, comprising in addition to iron alloying elements selected from the group comprising aluminum, silicon, chromium, nickel, molybdenum, titanium, niobium, tungsten, vanadium, cobalt and mixtures thereof, e.g. V2A steel; V4A steel; Cr steel; CrNi steel; CrNiMo steel; WStE 26 to 36; WStE 39 to 51; 15 MnNi 53; 20 MnMoNi 55; 19 Mn 5; 15 Mo 3; 13 CrMo 44; 10 CrMo 9 10; 14 MoV 6 3.

[0142] A base layer of the surface-structured substrate, which has a surface formed from a structured and an unstructured region, can also comprise or be formed from a metal, preferably copper and / or aluminum, an alloy and / or a semiconductor, preferably silicon.

[0143] What is characteristic in each case is that in a layer or partial layer of the surface-structured substrate, which comprises or is formed from a metal, preferably copper and / or aluminum, an alloy and / or a semiconductor, preferably silicon, a structured region is formed or the structured region extends at least into such a partial layer.

[0144] The material of the cover layer and / or the base layer may have a melting point of less than 1,400°C, preferably less than 1,200°C, particularly preferably less than 1,100°C. This particularly applies to the layer having the structured surface.

[0145] Preferably, in the structured region, preferably at the surface (i.e., at the interface of the structured region of the substrate), in particular when using a metal and / or an alloy, the oxygen content is in the range of at least 8 to 40 wt. %, preferably in the range of at least 10 to 30 wt. %, particularly preferably in the range of at least 15 to 30 wt. %. The oxygen content has the advantage that it leads to surface passivation in the structured region, which, in interaction with the pure black marking generated by the topography, leads to a combination effect, whereby the proportion of absorbed electromagnetic radiation, in particular visible light, for example expressed as a gloss factor (as defined herein), is increased.

[0146] According to a preferred embodiment, in the structured region, the mass ratio of the metal and / or a metal of the alloy to the oxidized form of the metal is in the range of 95:5 to 50:50, preferably in the range of 90:10 to 50:50, particularly preferably in the range of 85:15 to 60:40, in particular in the range of 80:20 to 60:40. Alternatively, no or only slight oxidation may occur.

[0147] Base layer / base body

[0148] According to a preferred embodiment, the first outer surface of the surface-structured substrate is formed as a component of a cover layer, and the cover layer is formed adjacent to a base layer. In this case, the base layer for the cover layer can be formed as a shaping base body, on whose surface the cover layer is at least partially arranged. In particular, if the base layer is formed as a shaping base body, the cover layer is applied to it.

[0149] In the sense of this invention, the base layer is a substrate which shapes the surface-structured substrate, wherein at least one cover layer or partial cover layer, such as a layer of at least one metal, preferably copper and / or aluminum, an alloy and / or a semiconductor, preferably silicon, is arranged adjacent thereto.

[0150] For the purposes of the invention, the term "shaping base body" refers to an object with a structural shape to which this shape has been actively given, and which has been manufactured, for example, by non-cutting forming (e.g., by pressing, compression molding, or injection molding) in fully enclosed tools. Alternatively, the shaped body is a deliberately shaped body / object in the form of a blank.

[0151] According to a preferred embodiment, the base layer, in particular the shaping base body, is formed from a transparent or partially transparent or translucent material, preferably glass, or comprises a transparent or partially transparent or translucent material, preferably glass. The material forming the base layer or the shaping base body can also be selected from the group of plastics, in particular transparent or partially transparent or translucent plastics.

[0152] Effects to be achieved

[0153] Different properties can be created both within the black marking area and in other areas of the substrate surface. To do this, the structuring is adjusted accordingly within and / or outside the black marking area, so that the corresponding properties are generated based on the introduced surface irregularities.

[0154] Optical effects:

[0155] Antireflection

[0156] In principle, a portion of the incident electromagnetic radiation is partially reflected at surfaces or interfaces, depending on the material composition. The remaining electromagnetic radiation is transmitted into the substrate and at least partially absorbed there.

[0157] For the purposes of the invention, anti-reflection properties herein relate in particular to the increased transmission or diffraction of incident electromagnetic radiation with wavelengths in the spectral range optically visible to humans, in particular 380 to 780 nm, or in the range of ultraviolet radiation (in particular 100 to 380 nm) or infrared radiation (in particular 780 to 10,000 nm), so that the electromagnetic radiation is not reflected but is preferably absorbed by the substrate.

[0158] To produce a surface having anti-reflection properties, the depressions, in particular the cones or inverse cones or the groove-shaped depressions or the groove-shaped elevations, of an interference pixel according to a preferred embodiment of the present invention have an average structural depth or profile depth on average d50 in the range from 5 nm to 10 pm, in particular in the range from 10 nm to 5 pm, particularly preferably in the range from 50 nm to 800 nm, very particularly preferably from 100 nm to 500 nm. The structural depth of the inverse cones of an interference pixel is generally described by the average structural depth (d50), which defines the proportions of cones within an interference pixel with a certain structural depth smaller or greater than the specified value for the structural depth.Antireflection properties on a surface are preferably achieved by forming the structured region by a periodic structure, preferably by a periodic dot structure, in the nanoscale (submicrometer range) consisting of depressions, preferably inverse cones or cones, with average dimensions in the submicrometer range, or by at least having such a periodic dot structure in the nanoscale. The periodic dot structure of an interference pixel has, in particular, an interference period of 100 nm to 1,000 nm, particularly preferably 200 nm to 700 nm, and most preferably 200 nm to 450 nm.

[0159] The structural parameters defined herein for producing a surface having anti-reflection properties, such as the interference period and structure depth, in particular the interference period, advantageously allow the proportion of reflected radiation at an interface of a substrate, preferably within the black marking area, to be reduced by at least 50%, preferably at least 70%, particularly preferably at least 80%, very particularly preferably at least 90%, in particular at least 95%.

[0160] The anti-reflection properties for visible light are particularly achieved when the dimensions of the structure produced, i.e. the interference period and dimensions of the depressions, in particular of the individual cones or inverse cones, are in ranges smaller than the wavelength of visible light, i.e. preferably below 700 nm.

[0161] In physics, reflection refers to the rebound of an electromagnetic wave at an interface between materials with different refractive indices. The angle of reflection and the angle of transmission of light in transparent substrates can generally be calculated using Snell's law of refraction: n sln 6 = n 2 sin δ 2, where m and n 2 indicate the refractive index of the surrounding medium, for example, air, and the material of the cover or base layer, and δ 1 and δ 2 indicate the angles of the incident and reflected beams, respectively.

[0162] Due to the periodic structure, in particular the periodic dot structure, on the outer surface of the cover or base layer, the refractive index of the cover or base layer changes in the area of ​​the surface or interface, resulting in a gradual refractive index. This results in light with wavelengths longer than the interference period (p n) of the periodic dot structure is transmitted more frequently. Light with wavelengths less than or equal to the periodic structure, preferably the periodic dot structure, is diffracted at the surface.

[0163] In the context of the invention, anti-reflection properties refer to structures, preferably point structures, but also line structures, whose dimensions lie within the range of the incident electromagnetic wave, so that the refractive index difference is "softened," resulting in the incoming wave being coupled into the corresponding layer. In this case, a portion of the incoming electromagnetic wave may also be slightly deflected away from the observer.

[0164] Additionally, the term "anti-reflection properties" within the meaning of the invention also encompasses the fact that the refractive index at the boundary between the first medium, for example, air, and the substrate is gradual, so that there is no clear transition from one medium to the other for the incident electromagnetic wave, and the incident electromagnetic wave is transmitted more strongly. An anti-reflection property is preferably understood to mean visible light.

[0165] The refractive index of the structured substrate is gradual due to the created periodic dot structure. It decreases over the height of the structure, so that no clear medium-to-medium transition exists. This results in increased transmission of incoming electromagnetic waves with a wavelength longer than the interference period of the created structure, preferably a dot structure, and in the diffraction of incoming electromagnetic waves with a wavelength in the range of the interference period of the created structure into the cover or base layer.

[0166] For the purposes of the invention, a surface-structured substrate with anti-reflection properties also describes such a substrate which has a structured region consisting of superimposed structures, i.e., wherein a further structure is superimposed on the first periodic structure, wherein at least one structure has dimensions in the micrometer or submicrometer range, and wherein at least one structure is formed from depressions, in particular from pegs or inverse pegs or groove-shaped depressions or groove-shaped elevations (as defined herein), which can be generated in particular by interfering laser beams. Preferably, the further structure is a line structure consisting of groove-shaped depressions or groove-shaped elevations or a further periodic dot structure consisting of pegs or inverse pegs.

[0167] This makes it possible to adjust several surface properties simultaneously.

[0168] For example, when using interfering laser beams, the structured area, in particular the structure of overlapping periodic structures, can be optimally adapted to the requirements of the respective application by appropriately designing the parameters, in particular the process parameters (selection of the laser radiation source, arrangement of the optical elements).

[0169] According to one possible embodiment, a surface-structured substrate with a first outer surface having anti-reflective properties has a periodic structure with a first interference period, which forms the structured region. This advantageously allows the anti-reflective properties to be adjusted very reliably and with good reproducibility.

[0170] In contrast to conventional methods for influencing surface or interface properties (e.g., etching, sandblasting, polymer coatings), when using laser structure application methods, in particular direct laser interference structuring, it is not necessary for the entire surface to be structured. The proportion of the structured surface (degree of coverage of depressions, in particular inverse cones, per unit area, which is determined by the number and diameter or width of the depressions, preferably the inverse cones), i.e., the proportion of the structured area of ​​the surface, is preferably 3% to 99%, particularly preferably 5% to 80%, very particularly preferably 7% to 70%, in particular 10% to 50%.This not only allows for better detectability compared to conventional methods for structuring / coating surfaces, but also has the advantage that fewer defects or more vulnerable structures are introduced into the plane of the surface and / or interface in order to achieve the properties defined herein.

[0171] Reduced reflection due to the trap effect

[0172] According to an advantageous embodiment, the surface irregularities are formed as inverted cones and / or groove-shaped depressions. Thus, a portion of the rays reflected from the surface again strikes a point within the same surface irregularity, and a portion of the electromagnetic radiation is again transmitted into the substrate. This advantageously increases the proportion of electromagnetic radiation transmitted into and absorbed by the substrate, thus reducing reflection. For the purposes of the invention, this phenomenon is referred to as reduced reflection due to the trapping effect.

[0173] The reduction of reflection due to the trap effect (as defined herein) by the formation of suitable structured and unstructured areas on the first outer surface of a substrate leads in particular to reduced glare effects and the optical impression can generally be improved by a matt impression.

[0174] A matte appearance refers to the property of a surface to scatter incident light across the surface. Thus, unlike glossy surfaces, light is not reflected primarily in one spatial direction.

[0175] Reducing reflection due to the trap effect (as defined herein) by forming suitable structured and unstructured regions on the outer surface and / or inner surface of a substrate is of great importance for reducing general reflection, especially also for reducing specular reflection. The surface irregularities are formed so deep that a light beam reflected within a surface irregularity re-impinges on a point within the surface irregularity, allowing a portion of it to penetrate the substrate, resulting in both transmission and absorption. In any case, such deep structures reduce reflection.

[0176] According to a preferred embodiment of the invention, the structured regions which reduce the reflection due to the trapping effect within the structured regions are arranged in such a way that, with respect to the direction of incidence of electromagnetic radiation, preferably light, inverse pegs and / or groove-shaped depressions are arranged at this interface into which the light enters, in such a way that they are formed into the substrate.

[0177] Such a structure for reducing reflection due to the trap effect can also be created by forming a suitable structured and unstructured region, in particular a structured region, on the outer surface and / or inner surface of the substrate. When utilizing the trap effect, the lateral surface of the pegs or inverse pegs serves as a mirror surface, preferably a quasi-homogeneous mirror surface, which reflects the portion of reflected incident electromagnetic radiation within the inverse pegs and / or groove-shaped depressions up to the saddle point. At each further reflection point within the lateral surface, a portion of the (remaining) electromagnetic radiation is coupled into the substrate, whose outer surface and / or inner surface is formed from such a structured and an unstructured region.According to a preferred embodiment of the invention, the side surface of the inverse pins or groove-shaped depressions is smooth.

[0178] According to a further embodiment of the invention, reduced reflection is also achieved by changing the material properties through the structuring process of the substrate. Particularly in the case of a substrate made of a polymer, the substrate material also burns in the area of ​​the black marking, resulting in additional blackening of the substrate in the area of ​​the black marking due to a change in the surface material. This effect is caused in particular by the thermal reaction and degradation of the polymer structure under the influence of the laser pulses. Functional groups or the polymer backbone can be broken down or converted, which can lead to the release of volatile, low-molecular compounds such as nitrogen (N2), carbon monoxide / carbon dioxide (CO / CO2), and water (H2O). This process creates compounds with increased absorption of electromagnetic waves, e.g.polycyclic aromatic compounds or polyunsaturated compounds, especially in the UV / VIS and IR spectrum, which significantly improves the absorption properties of the substrate in the black marking areas. This surface modification contributes to increasing the efficiency of black marking and enables more precise control of the optical properties of the material.

[0179] Anti-glare

[0180] According to an advantageous embodiment, a structuring having anti-glare properties can be produced on the substrate, in particular in the black marking area.

[0181] Glare effects can be reduced with the help of a surface structuring described herein, in particular anti-glare structuring. An anti-glare structure scatters incident electromagnetic radiation, e.g., light, at a plane of the substrate, in particular the surface of the substrate, so that reflection of this electromagnetic radiation can be significantly reduced.

[0182] In the context of the invention, glare is understood to mean the reflection of light from a light source (e.g. the sun) on a substrate, e.g. a glass pane or a metal element.

[0183] With the help of an anti-glare surface treatment (typically achieved through coatings in the prior art), these glare effects can be reduced. An anti-glare structure scatters incident light on the surface, significantly reducing reflections. The surface then appears matte in this area.

[0184] According to a preferred embodiment of the invention, the interference periods of the dot structure of the first interference pixel and the period of the second interference pixel are identical.

[0185] According to a preferred embodiment of the present invention, the method according to step b) comprises applying at least one further type of interference pixel with a further interference period (p n), for example a third interference pixel (12) with a third interference period (pa) onto the surface of the substrate processed in step b), in particular by means of laser ablation, wherein the further, for example the third interference pixel (12) is arranged superimposed on the first interference pixel (10) and second interference pixel (11) according to the features defined herein. The ratio of the further interference period (p n ) to the other interference periods in the range of preferably 20:1 to 1:20, preferably in the range of 10:1 to 1:10, particularly preferably in the range of 5:1 to 1:5, in particular 3:1 to 1:3, whereby the properties defined herein, in particular the anti-glare properties or the reduction of reflection due to the trap effect within the black marking area can be optimized.

[0186] The periodic structures thus generated within an interference pixel, preferably periodic dot structures, are designed as periodically arranged depressions, preferably pegs or inverse pegs. The interference period (i.e. the distance between the depressions, preferably the distance between the vertices of two adjacent inverse pegs - or the height centers relative to pegs or the center lines of the groove-shaped depressions or the center lines of the groove-shaped elevations) of a periodic structure, preferably a first periodic structure, in particular on a surface of the cover or base layer which has anti-glare properties, is on average in the range from 1 pm to 50 pm, preferably in the range from 5 pm to 50 pm, particularly preferably in the range from 10 pm to 30 pm.

[0187] Advantageously, the individual pixels of one type of interference pixel, i.e., with the same interference period and average structure depth, e.g., of a first interference pixel, a second interference pixel, and / or a further interference pixel, which are arranged adjacently and repetitively offset from one another, can globally (i.e., over the extent of the plane to be structured) optionally form a periodic or a non-periodic structure, preferably a periodic or non-periodic dot structure. A fully periodic dot structure is generated or exists when the preceding pixel and the following pixel of one type of interference pixel are each offset by a whole multiple (e.g., 2, 3, 4, 5) of the interference period (p n ) are shifted from each other in one spatial direction. This results in a fully periodic pattern over the extent of the plane to be structured, the period of which corresponds to the interference period (p n). A quasi-periodic dot structure is created or exists when the preceding pixel and the following pixel of a type of interference pixel are each spaced apart by an equal multiple (e.g. 0.5; 1.3; 2.6) of the interference period (p n ) are shifted from each other in one spatial direction.

[0188] In contrast, a non-periodic dot structure is created or exists when the interference period of the subsequent pixel is varied relative to the neighboring, previous pixel and / or when neighboring pixels arranged repetitively offset from one another are rotated, e.g., are applied in a successively rotated manner.

[0189] A characteristic feature of this technique is that the structured region is formed by a superposition of several periodic structures. In particular, several interference pixels are arranged repetitively adjacent to one another in such a way that the generated global structure, i.e., the structure that forms the structured region, is preferably non-periodic.

[0190] This preferably creates many scattering centers on the surface, which, due to their irregularity, scatter the electromagnetic radiation, i.e., the light, in different directions. This advantageously avoids strong reflections in individual directions. Furthermore, effects such as a rainbow-like shimmer effect caused by refraction effects due to periodicity can be advantageously avoided or at least reduced. To create such a non-periodic structure, preferably at least 70%, preferably at least 90%, particularly preferably at least 98%, of the neighboring interference pixels have different structural parameters, i.e., at least one different structural parameter or at least two different structural parameters selected from the interference period, the structural depth or average structural depth, and the arrangement of the cones or inverse cones within an interference pixel.For example, the position of the recesses, in particular the studs or inverse studs, can be changed to obtain a non-periodic global structure. This advantageously allows a suitable global structure with low periodicity to be obtained at high process speeds, thereby advantageously avoiding the moiré effect and diffraction effects. The change in the structural parameter(s) preferably occurs according to a random distribution, in particular using a stochastic method.

[0191] According to a preferred embodiment of the present invention, the dot structure formed by adjacent, repetitively offset pixels of a type of interference pixel is a fully periodic dot structure or a quasi-periodic dot structure (each as defined above).

[0192] To produce a surface having anti-glare properties, the depressions, preferably the cones or inverse cones, of an interference pixel according to a preferred embodiment of the present invention have a mean structural depth or profile depth on average d50 in the range from 5 nm to 20 pm, particularly preferably in the range from 50 nm to 10 pm, very particularly preferably from 100 nm to 5 pm, even more preferably 200 nm to 2 pm. The structural depth of the inverse cones of an interference pixel is generally described by the mean structural depth (d50), which defines the proportions of cones within an interference pixel with a certain structural depth smaller or greater than the specified value for the structural depth.

[0193] It can be provided that first interference pixels and / or second interference pixels arranged adjacent to one another have, at least to a high extent of at least 70%, preferably at least 90%, preferably at least 98%, varying structural parameters, preferably selected from the group comprising the interference period of the interference pixel, the structural depth of the depressions, preferably of the inverse pegs, the diameter of the pegs or inverse pegs, the width of the groove-shaped depressions or the groove-shaped elevations, the shape of the pegs or inverse pegs and the size of the pegs or inverse pegs. Preferably, a further possible structural parameter is the arrangement or position of the depressions, preferably of the pegs or inverse pegs. This advantageously makes it possible to achieve a high degree of disorder, i.e.non-periodic structures are created, thereby minimizing or preventing unwanted or disturbing optical effects, such as moiré effects or color effects caused by diffraction on applied microstructures.

[0194] According to a preferred embodiment of the invention, the interference period of the dot structure of at least each further interference pixel of a type, for example each interference pixel of a first interference pixel, each interference pixel of a second interference pixel and / or each interference pixel of a third interference pixel, is substantially identical, i.e. differs by a maximum of 0% to 2.0%, particularly preferably by a maximum of 0 to 1.0%. Most preferably, the interference periods are identical. As a result, the parameters of the laser structuring device, in particular of the laser interference structuring device for applying the interference pixels to the plane of the substrate, can be kept constant, which minimizes the effort and the formation of defective structures.

[0195] According to a preferred embodiment of the present invention, the adjacent, repetitively offset interference pixels of one type, for example the first interference pixel, the second interference pixel and / or the third interference pixel, are rotated successively relative to the preceding interference pixel of this one type about an axis of rotation (i.e. a normal to the plane) arranged within the interference pixel (preferably about a central one), for example alternately or successively rotated relative to the one before it. Preferably, the subsequent interference pixel is rotated relative to the preceding interference pixel of the interference pixels of one type in the range around 51° to 90°, furthermore in the range around 3° to 85°, particularly preferably around 5° to 80°, 10° to 75°, very particularly preferably around 10° to 75°, in particular in the range around 15° to 60°.As a result, a high degree of disorder, i.e. non-periodic structures, is generated globally over a plane of the substrate that is spanned by a surface of the substrate or within the volume of the substrate, which also minimizes or prevents undesired or disturbing optical effects, such as moiré effects or color effects that arise from diffraction on applied microstructures.

[0196] In general, the aim of generating suitable anti-glare properties is to generate a dot structure with broken periodicity, i.e., without resulting periodicity, through the specific selection of the structural parameters of the first and second interference pixels and each additional type of interference pixel. The generated dot structures are therefore preferably arranged non-periodically, with the interference periods of the first and second interference pixels, or each additional type of interference pixel, preferably being different (not identical) from one another. Periodic effects that disrupt the resulting image can thus be advantageously avoided.

[0197] A superposition of first and second interference pixels, which have identical interference periods, can result in periodic dot structures in which the undesirable moiré effect occurs.

[0198] A high degree of disorder also prevents adverse changes in color behavior, which can occur due to diffraction effects on the introduced structures.

[0199] The existing dot structure leads to a scattering behavior of the incident light, which involves a multitude of minimal deflection processes of the photons at the introduced dot structures. The existing periodicity of the dot structures can thus lead to an increase in the deflection of the photons, i.e., the light, in certain directions, creating a glittering effect. While this effect is desirable for certain applications, it should be avoided for many others. The generation of non-periodic structures advantageously leads to a reduction or elimination of these glittering effects.

[0200] In the aforementioned case, the offset between the interference pixel of a first type and the interference pixel of a second type, for example the second interference pixel and the first interference pixel, is in the range of 5% < x < 50%, preferably in the range of 10% < x < 50%, in particular in the range of 20% < x < 50%, particularly preferably in the range of 25% < x < 45% of the interference period. If the periodic dot structure is designed such that an interference pixel of a further type is provided, at least a third interference pixel, this is arranged superimposed on the interference pixel of the previous type such that the offset between the interference pixel of the further type, for example the third interference pixel, and the second interference pixel is in the range of 5% < x < 50%, preferably in the range of 10% < x < 50%, in particular in the range of 20% < x < 50%, particularly preferably in the range of 25% < x < 45% of the interference period.An offset which lies below the interference period leads to an increase in the structure density or density of the point structure, which results in an increased scattering cross section and advantageously a greater scattering effect or a stronger reduction of the directed reflection.

[0201] According to a preferred embodiment of the present invention, the structured substrate, in particular the dot structure applied to the surface of the substrate, has at least one further type of interference pixel with a further interference period, for example a third interference pixel with a third interference period, wherein the further, for example the third interference pixel is arranged superimposed on the first interference pixel and the second interference pixel according to the aforementioned claims. As a result, further defects (ie

[0202] Dot structures in the micro and sub-micrometer range) can be created. A higher number of inverse cones increases the number of scattering centers and reduces specular reflection. This can also advantageously increase the degree of disorder, i.e. non-periodic structures, whereby undesired or disruptive optical effects such as moiré effects or color effects caused by diffraction on applied microstructures can be minimized or prevented. Furthermore, when used in displays, for example, this reduces or prevents the occurrence of a glitter effect, which occurs as a result of surface structures larger than or equal to the number of display pixels. With a glitter effect, a display pixel only illuminates part of the surface feature, resulting in scattering effects that are perceived macroscopically as a periodic pattern.

[0203] The structure defined herein for generating anti-glare properties, preferably a dot structure, is preferably a non-periodic dot structure composed of cones or inverse cones with average dimensions in the micrometer range, wherein the structure of an interference pixel in particular has an average distance, relative to the respective saddle point or height center of two adjacent cones of an interference pixel, of 1 pm to 50 pm, particularly preferably 5 pm to 50 pm, and most preferably 10 pm to 30 pm. A further structure in the nanometer range can be superimposed on this preferably anti-periodic dot structure in the micrometer range, wherein the average dimension of the superimposed structure preferably has dimensions in the range of the laser wavelength λ or λ / 2, in particular from 100 nm to 1,000 nm, particularly preferably from 200 nm to 500 nm. For the purposes of the invention, such a structure is also referred to as a hierarchical structure.

[0204] The invention also encompasses a surface-structured substrate with anti-glare properties, wherein a first outer surface has anti-glare properties. Preferably, such a surface further comprises a second periodic structure, preferably a second periodic dot structure, with a second interference period.

[0205] On the one hand, varying the interference period can reduce the periodicity of the structure, especially the global structure, thereby improving the anti-glare effect. Furthermore, a second periodic structure can also create additional properties.

[0206] Thus, the invention also encompasses a surface-structured substrate with anti-glare properties, wherein a first outer surface, particularly within the black marking area, has anti-glare properties and also other properties, such as an increased heat transfer coefficient at the surface. The superimposed structures are created as described in the corresponding sections on the specific properties.

[0207] PROCEDURE

[0208] The present invention also encompasses a method for producing a surface-structured substrate, as defined herein, wherein the surface-structured substrate has at least one first outer surface with a black marking region, wherein the black marking region, the first outer surface, is formed by a structured region and an unstructured region. The method for producing a structured substrate (as defined herein) preferably comprises the following steps: a) providing a substrate to be structured, wherein the substrate to be structured has an interface, wherein the interface is formed as a direct contact surface between the surface of the substrate to be structured and an adjacent medium, for example a gas or an auxiliary layer,wherein the substrate to be structured or the medium adjacent thereto comprises or consists of a material with a thermal conductivity of at least 20 W / (m K), preferably at least 50 W / (m K), more preferably at least 100 W / (m K), particularly preferably at least 200 W / (m K), measured at 20 °C, b) applying a structured region to the surface to be structured, in particular to a first outer surface of the substrate to be structured, in particular by means of laser ablation (as defined herein), whereby a black marking region is created on the surface to be structured, wherein the structured region has at least one first interference pixel with a first interference period (pi), wherein the first interference pixel is formed from a first periodic structure of at least three surface irregularities, wherein the surface irregularities are in particular designed as a single line structure, a single dot structure,a plurality of superimposed line structures, a plurality of superimposed dot structures, or even superimposed dot and line structures can be formed, wherein the distance between two adjacent surface irregularities amounts to a first interference period (pi), wherein the structured region further comprises a plurality of further interference pixels arranged offset from one another, wherein the structured region is formed by superimposed application of the first interference pixels () on a surface or in the volume within the interface of the substrate, wherein the first interference pixels have an overlap, in particular a pixel-to-pixel overlap (as defined herein), of at least 90%, preferably of at least 95%, particularly preferably of at least 99%, most particularly preferably of at least 99.5%.

[0209] Particularly advantageously, this allows a surface structuring to be created on the substrate which has a black marking with a reduced reflection compared to the unstructured area of ​​the substrate.

[0210] Preferably, the first interference period (pi) is in the range from 50 nm to 200 pm, preferably from 1 pm to 45 pm.

[0211] Further preferably, the black marking area has a ratio of the real surface to the projected surface of at least 120%.

[0212] According to the invention, the structured region on a surface of the substrate is formed at least by superimposing a plurality of first interference pixels with a first interference period (pi) on the first outer surface of the substrate, whereby an interference pixel-to-interference pixel overlap (herein also referred to as "overlap of the interference pixels" or, when applied by means of laser structure application methods, in particular by means of laser interference structuring, as "pulse-to-pulse overlap") is created. This means that a first interference pixel is superimposed on at least one further first interference pixel with the first interference period (pi) and / or a second interference pixel with a second interference period (P2) and / or a further interference pixel with a further interference period (p n) can be arranged offset from one another in such a way that, for example, at least 50% of the offset interference pixels have an overlap of at least 95%, preferably of at least 97%, particularly preferably of at least 99%, very particularly preferably of at least 99.5%, even more preferably of at least 99.8% with a neighboring interference pixel, preferably with a plurality of neighboring interference pixels. Advantageously, the very close arrangement of periodic structures arranged adjacent to one another, in particular periodic dot structures and / or line structures, e.g.By means of adjacent, repetitively offset pixels of a type of interference pixel, the surface area in the structured region of the substrate is enlarged even more in relation to the projected surface, in particular to at least 200%, particularly preferably to at least 250%, thereby advantageously improving the heat transfer properties, in particular increasing the heat transfer coefficient. Thus, better heat dissipation from a substrate or element, e.g., a component, can be achieved.

[0213] Preferably, the structuring of the surface of a substrate, ie the application of the structured regions comprising a first, second, third and / or further interference pixel, is carried out by a mechanical method, by means of chemical (post-)treatment and / or by means of a laser structure application method, in particular by means of laser interference structuring.

[0214] To produce substrates whose outer surface is at least partially formed from a structured and an unstructured region, lithography, in particular photolithography or imprint lithography, such as nano-imprint lithography, can be used as a mechanical process. In lithography, a sacrificial layer is generally arranged on the surface of the substrate to be structured. The sacrificial layer serves to mask the surface to be structured and can be removed, in particular completely, after lithography. For example, the sacrificial layer can be applied to the surface to be structured and subsequently structured. The lateral structure of the sacrificial layer can then be transferred to the surface of the substrate, in particular by means of an etching process.In photolithography, the sacrificial layer is usually a photosensitive resist layer whose chemical properties are locally modified by irradiation through a suitably structured mask, such as a metal mask, allowing the formation of structured regions in the sacrificial layer. This process can achieve structuring of surfaces with feature sizes of a few micrometers in the lateral direction. Both regular and irregular structures can be produced in this way.

[0215] Imprint lithography, e.g. nano-imprint lithography, is a microforming process or contact structuring process in which the surface of a substrate, e.g. the sacrificial layer, is structured using a suitably structured mold. This mold, such as a suitably structured stamp, is pressed into the surface of the substrate to be structured. The substrate to be structured can, for example, contain a thermoplastic polymer (Thermoplastic Nano Imprint Lithography, T-NIL) or a photosensitive material (Photo Nano Imprint Lithography, P-NIL). However, the substrate to be structured can also comprise or consist of an at least partially softened metal and / or an alloy. Metals with a low melting point or softening point, such as, for example,Copper (Cu), silver (Ag), gold (Au), tin (Sn), lead (Pb), zinc (Zn), aluminum (Al), or mixtures or alloys thereof, such as copper alloys with tin, zinc, nickel and / or lead. Nano-imprint lithography can be used to structure surfaces in a particularly simple manner. In particular, particularly small lateral structure sizes, i.e. structures below 1 pm down to the range below 10 nm, can be produced. Nano-imprint lithography is therefore particularly suitable for producing structure sizes that are on the order of the wavelength of radiation in the infrared, visible, or ultraviolet spectral range, for example for the production of structures for a photonic grating. Such a process is particularly suitable if the structured regions of the substrate surface are to have a periodic point structure (as defined herein) formed from cones and / or inverse cones.To produce the mold, it is advisable to apply the negative of the desired periodic dot structure to the surface of the substrate to be structured, in particular a negative with a correspondingly complementary periodic structure, which is formed from inverse pegs and / or pegs, for the indirect application or generation of structures on another substrate, for example by laser structure application methods, in particular direct laser interference structuring, and to transfer this negative to the surface of the substrate to be structured.

[0216] In a preferred embodiment of the invention, the structuring of the substrate surface can be carried out using laser structuring methods, in particular direct laser interference structuring. A periodic intensity distribution is generated on the surface of the substrate or within its volume by interference of pulsed laser beams by splitting the original laser beam into several partial beams and subsequently superimposing these partial beams at any fixed point (focusing point) on the surface of the substrate or within the volume of the substrate.

[0217] A structured area on an outer surface of a substrate to be structured can be created as follows:

[0218] A substrate to be structured is provided, preferably a substrate that is flat on at least one side, which is located on a holding device. A laser beam is emitted from a laser radiation source. This laser beam is split into at least three, particularly preferably at least four partial beams by a beam splitter element, which can also be referred to as an optical beam splitter element. The partial beams thus generated impinge on a focusing element, which focuses (bundles) the at least three, particularly preferably four partial beams on the surface of the substrate, preferably a substrate that is flat on at least one side, so that the partial beams interfere constructively and destructively on the surface of the substrate.Thus, a periodic dot structure in the micrometer and / or submicrometer range is created on the surface of the substrate, preferably a flat and / or transparent substrate, by laser interference processing. The at least three partial beams are superimposed to create a 2D pattern.

[0219] According to one variant of the method, the periodic dot structure is created within an interference pixel on the outer surface of the substrate to be structured using a single laser pulse, referred to herein as single irradiation. Single irradiation means that the interference pixel is preferably exposed only once within a processing step using a single laser pulse. Thus, a dot structure with one interference period is created within an interference pixel by exposure to only one laser pulse. Adjacent interference pixels preferably do not overlap, so that a resulting inverse cone is not illuminated again. The maximum laser pulse energy depends on the pixel size and the material. The minimum pulse energy is preferably in the range from 50 pJ to 20 mJ, particularly preferably in the range from 300 pJ to 800 pJ.This advantageously allows for high process speeds. Furthermore, the use of a single irradiation can prevent the occurrence of quasi-periodic wave structures, so-called LIPSS, caused by uncontrolled self-organization processes that alter the optical properties of the substrate surface. Consequently, the occurrence of LIPSS structures can be prevented by a single irradiation. This allows for significantly more precise process control and reliably achieves the desired properties of the black marking area.

[0220] The fact that the periodic dot structure within an interference pixel is generated by applying a single laser pulse using single irradiation also has the advantage that very small structure depths can be created, which is particularly advantageous for thin substrates.

[0221] Preferably, single irradiation produces shallow structural depths that can be adjusted according to the material or material composition of the substrate. For example, structural depths in the range from 0.05 pm to 2 pm, preferably from 0.1 pm to 1 pm, can be achieved in this way. For example, this can also be used to structure substrates that are additionally characterized by anti-reflection properties, with the structural depths being in the range from 5 nm to 200 nm, particularly preferably in the range from 5 nm to 150 nm, and most preferably 10 nm to 100 nm. Using a single laser pulse ensures that the structural depths of the periodic dot structure are shallow. This advantageously ensures that the optical properties of the substrate are not impaired compared to the unstructured substrate.

[0222] Notwithstanding this, structuring by means of single irradiation can also be provided for setting a pulse-to-pulse overlap. This means that a first interference pixel can be arranged offset from a second and / or further interference pixel in such a way that, for example, at least 50% of the offset interference pixels have an overlap of at least 95%, preferably of at least 97%, particularly preferably of at least 99%, and most preferably of at least 99.5% with a neighboring interference pixel, preferably with a plurality of neighboring interference pixels. Structuring by means of pulse-to-pulse overlap has the advantage that at least individual structural elements generated within a first, second, and / or further interference pixel are irradiated multiple times.This allows self-organization processes to form a quasi-periodic line structure superimposed on the periodic dot structure as a wave structure, particularly a so-called LIPSS. Advantageously, hierarchical structures can be created quickly and effectively on the substrate surface, allowing the surface roughness of the wall of a periodic dot structure to be increased, particularly in the nanometer and / or submicrometer range, resulting in an increase in the surface area.

[0223] In particular, achieving the desired interference periods of the LIPSS generated by the self-assembly processes depends on the material properties of the substrate to be patterned and the properties of the laser beam used for patterning, particularly the wavelength of the laser beam. A desired interference period can therefore be adjusted by selecting the appropriate laser radiation source.

[0224] According to a further embodiment of the invention, the same interference pixel is processed by means of several consecutive laser pulses through multiple irradiation. Multiple irradiation means that the same area of ​​the substrate to be structured is processed by several consecutive laser pulses, wherein the 2D pattern of a first pulse generated by the superposition of partial beams is congruent or essentially congruent (i.e., with a topological shift of less than 1.0%, preferably less than 0.5%) with a second and / or further pulse. Thus, a dot structure with an interference period within an interference pixel is exposed several times, with a resulting inverse cone being exposed again one or more times. The pulse length can be adjusted by the user.

[0225] In particular, in this method, the same interference pixel is processed by means of multiple irradiation. Thus, as a result of the successive multiple irradiation of an interference pixel, in particular at least three, particularly preferably at least four consecutive pulses with identical process parameters, a quasi-periodic line structure superimposed on the periodic structure, in particular a periodic dot structure, forms as a wave structure through self-organization processes. Process parameters within the meaning of the invention include, for example, the setting of the distance between the beam splitter element and the focusing element, the laser pulse duration, the laser pulse energy, the laser wavelength, and / or the position of the interference region on the substrate. Self-organization processes refer in particular to so-called LIPSS, as known from the prior art.LIPSS occur as a result of partial heating of the substrate surface and its subsequent solidification in the form of regular, quasi-periodic (as defined herein) wave structures. Advantageously, hierarchical structures can be created quickly and effectively on the surface of the substrate, thereby increasing the surface roughness of the wall of a periodic dot structure, resulting in an enlargement of the surface area. Readjustment of the laser interference device and / or realignment of the substrate is not necessary for this. In addition, the structural parameters of the periodic dot structure, in particular the structure depth, are thus also adjustable. A shallow structure depth is preferably achieved by adjusting the process parameters, in particular the laser pulse energy, such that the energy input due to the multiple irradiation per interference pixel remains as low as possible.

[0226] According to a further embodiment of the invention, a further periodic dot structure or periodic line structure with an interference period different from the interference period of the first periodic structure, the second periodic structure and / or a further periodic structure is applied to the substrate by multiple irradiation with mutually differing process parameters. The differing process parameters relate in particular to the distance of the beam splitter element from the focusing element, whereby the interference period of the further periodic dot structure or line structure is changed compared to the first periodic dot structure. However, an additional change in the laser pulse duration and / or energy is also possible. Thus, a flexible second structure with dimensions in the micrometer and / or submicrometer range can advantageously be applied to the substrate, which is independent of the first periodic dot structure.This ensures easy alignment of the interference pixels on the substrate. Furthermore, the proportion of structured area on the substrate surface is increased, allowing certain properties, such as the trapping effect to reduce reflection, to play a greater role.

[0227] The laser pulse duration is preferably in the range from 50 fs to 100 ns, preferably in the range from 500 fs to 50 ns, particularly preferably in the range from 800 fs to 20 ns, and most preferably in the range from 1 ps to 10 ns. This advantageously limits the energy so that defined structures can be created. This short laser pulse duration can prevent or at least minimize unwanted and / or uncontrolled melting of the substrate (e.g., in the form of a structural or chemical transformation), particularly as a result of local overheating, e.g., due to excessive energy input. This is particularly advantageous for the "sensitive" materials used herein which the substrates comprise or from which the substrates are made.

[0228] With longer pulses starting from 1 ns, more heat, i.e. energy, is introduced into the material and a larger amount of material is melted, forming local wavefronts (at the maxima) that can overlap and thus lead to large structure heights.

[0229] With shorter pulses up to 1 ns, especially up to 500 ps, ​​the material is removed more quickly. Relevant effects here are cold ablation or material sputtering, so that pits are more likely to form and little to no melting occurs.

[0230] The laser radiation source is preferably configured to emit wavelengths in the range from 100 nm to 15 pm (e.g., CO2 lasers in the range from 10.6 pm), most preferably in the range from 266 nm to 1,064 nm. Suitable laser radiation sources include, for example, UV laser beam sources (155 nm to 355 nm), laser beam sources that emit green light (532 nm), diode lasers (typically 800 nm to 1,000 nm), or laser beam sources that emit radiation in the near infrared (typically 1,064 nm), in particular with a wavelength in the range from 200 nm to 650 nm. Lasers suitable for microprocessing are known to the person skilled in the art and include, for example, HeNe lasers, HeAg lasers (approx. 224 nm), NeCu lasers (approx. 249 nm), Nd:YAG lasers (approx. 355 nm), YAG lasers (approx. 532 nm), InGaN lasers (approx. 532 nm).

[0231] The laser pulse energy is preferably 50 pJ to 20 mJ, more preferably 300 pJ to 800 pJ, and particularly preferably 500 to 800 pJ. This low laser pulse energy per laser pulse can prevent or at least minimize unwanted and / or uncontrolled melting of the substrate (e.g., in the form of a structural or chemical transformation), particularly as a result of local overheating, e.g., due to excessive energy input. This is particularly advantageous for the "sensitive" materials used herein that the substrates comprise or are made of.

[0232] According to an advantageous embodiment of the method, pulses in the ps range are used. This allows the energy input to be reduced and thus also the heat diffusion length to be reduced. This enables the creation of defined structures even in materials with high thermal conductivities. According to a preferred embodiment of the invention, the interference periods of the periodic structure of the first interference pixel (pi) and the interference periods of the second interference pixel (P2) and / or each further interference pixel (p n ) are identical.

[0233] According to an advantageous embodiment of the method, at least one structured region is applied indirectly to a surface to be structured, in particular to a first outer surface of the substrate to be structured, wherein an auxiliary layer is structured by a transparent base layer, wherein the transparent base layer is formed as the substrate to be structured. The laser beams, in particular the partial laser beams, are guided through the transparent base layer and focused onto the interface between the base layer and the auxiliary layer, which is preferably formed from a material as defined herein, in particular a metal, in particular onto the surface of the auxiliary layer. The material of the auxiliary layer is selected such that, in contrast to the base layer, it absorbs the laser light particularly well.This results in a partial melting of the auxiliary layer, particularly at the surface of the auxiliary layer, at the interface with the base layer. This allows a structure to be created on the base layer. The method according to the invention therefore also includes the provision of an auxiliary layer prior to the step of applying at least one structured region to an interface, particularly on the surface of the substrate to be structured.

[0234] Preferably, the surface of the substrate to be structured and the adjacent surface of the auxiliary layer are complementary (i.e., congruent) to each other, preferably planar, in particular plane-parallel to each other, which allows the surface of the substrate to be structured to be brought into congruence with the adjacent surface of the auxiliary layer.

[0235] By applying at least one structured region at an interface between the transparent base layer and the auxiliary layer, a structured region is formed by surface irregularities made of the material of the auxiliary layer through a material transfer from the auxiliary layer to the transparent base layer to be structured. In one embodiment, the auxiliary layer remains on the transparent base layer following step (b), wherein the transparent base layer is formed, for example, as a cover layer on the auxiliary layer, which, for example, assumes a different function in a component. Following step (b), the auxiliary layer can be removed from the base layer, leaving a cover layer on the base layer. This advantageously allows good heat dissipation to be achieved even on transparent materials.The base layer preferably comprises a transparent material (as defined herein with regard to partial transparency or translucency), preferably glass (e.g. borosilicate glasses, quartz glasses, alkali-alkaline earth silicate glasses (e.g. soda-lime glass), aluminosilicate glasses, metallic glasses), but also solid polymers (e.g. polycarbonates, such as Makrolon® and Apec®; polycarbonate blends, such as polycarbonate polyester (Makroblend®) and Bayblen®; polymethyl methacrylate, such as Plexiglas®; polyester; polyethylene terephthalate, polypropylene, polyethylene) and transparent ceramics (e.g. spinel ceramics, such as Mg-Al spinel, aluminum oxynitride (ALON), aluminum oxide, yttrium aluminum garnet, yttrium oxide or zirconium oxide) or mixtures thereof, or is formed from a transparent material, preferably glass. A suitable material for the transparent base layer is glass, which has a suitable transparency orTranslucency (each as defined herein), particularly in the visible light range.

[0236] According to the invention, the material of the base layer has a thermal conductivity of at least 20 W / (m K).

[0237] According to an advantageous embodiment of the invention, the transparent substrate, in particular the transparent base layer, and the surface thereof, in particular the heat transfer region thereof on the first outer surface, is formed from a structured and an unstructured region, after its structuring (ie after application of a first, second and / or further line and / or dot structure, as defined herein) continues to retain at least partially its transparency, so that it continues to be transparent or at least partially transparent.

[0238] Anti-glare

[0239] The invention also comprises a method for producing a laser-surface-structured substrate which has anti-glare properties, preferably by means of laser interference structuring, comprising the following steps: a) providing a substrate, b) applying at least one first interference pixel with a first interference period (p1) to a first outer surface of the substrate, wherein each of the first interference pixels () has a periodic structure of at least three surface irregularities, preferably pegs or inverse pegs or groove-shaped depressions or groove-shaped elevations, with a first interference period (p1), wherein the structured region is formed by superimposed application of the first interference pixels () to the first outer surface of the substrate.

[0240] A suitable method for generating anti-glare properties is the creation of hierarchical structures in which the interference period and / or average structure depth differ by at least a factor of 10. Hierarchical structures are particularly preferably created in such a way that self-organization processes effectively generate quasi-periodic structures, in particular quasi-periodic line structures, through multiple irradiation. This advantageously increases the surface roughness and easily increases the density of the depressions. This advantageously enables high processing speeds.

[0241] One possible embodiment of the method provides that a periodic structure is first created on a negative mold using a laser interference process and is then applied to the cover layer using the negative mold.

[0242] Alternatively, the process for creating the structures uses only a single irradiation, or at least a maximum of two or three irradiations, which can avoid LIPSS structures. This allows for highly reliable, reproducible structures to be created.

[0243] According to an advantageous variant for generating a non-periodic global structure, when generating neighboring interference pixels, at least one of the structure parameters differs to a high extent of at least 70%, preferably at least 90%, preferably at least 98%.

[0244] According to an advantageous embodiment of the invention, the adjacent, repetitively offset interference pixels of one type, e.g., the first interference pixel, the second interference pixel, and / or the third interference pixel, are generated using a laser interference method and successively modified relative to the preceding interference pixel of this one type by a phase shift in at least one of the at least two partial beams used for the laser interference method leading to a change in the position of the depressions within an interference pixel. For this purpose, the polarization of a partial beam used for interference structuring is preferably varied. As a result, the phase shift can lead to a change in the structural parameters, in particular the position of the depressions.

[0245] The inventors have further discovered that a modification of the structural parameters selected from the group comprising the interference period of the interference pixel, the structural depth of the inverse cones, the diameter of the inverse cones, the shape of the inverse cones, and the size of the inverse cones contributes to a preferred asymmetry (non-periodicity) within the global dot structure and thus to a desired asymmetry of the roughened structure. Thus, it can be provided that the aforementioned structural parameters of individual, adjacent, repetitively offset pixels of a type of interference pixel, e.g., the pixels of the first interference pixel, are modified alternately or successively, e.g., gradually. For example, it is possible to gradually increase the structural depth of each subsequent pixel to the adjacent, preceding pixel and gradually decrease it again starting at another pixel.For this purpose, it is suitable in the method that each subsequent pixel is applied to the surface of the substrate or in the volume of the substrate with a varying, for example, gradually increasing pulse energy (in the range as defined herein) and / or a gradually increasing pulse duration or pulse width (as defined herein). It can also be provided that an individual structural parameter is varied stochastically within a region when applying a pixel of a type of interference pixel. For example, in the method, the rotation of a subsequent pixel relative to the adjacent, previous pixel can not take place successively (i.e., uniformly), but alternately within the angular range defined herein, for example, first in one direction and then in another or the same direction, each with the same or a different angular displacement.

[0246] A preferred embodiment of the method provides that one or more structural parameters are distributed randomly or according to a stochastic method among the different interference pixels, so that most neighboring interference pixels do not have identical structural parameters.

[0247] LASER INTERFERENCE STRUCTURING DEVICE

[0248] As an example of a laser interference structuring device for producing a structured substrate, in particular a substrate with a black marking area, the present invention also relates to a laser interference structuring device for the direct laser interference structuring of a substrate, for example, flat and / or transparent substrates, comprising a laser radiation source (1) for emitting a laser beam, a beam splitter element (2) arranged in the beam path (3) of the laser beam, in particular in the beam path (3) of the laser beam emitted by the laser radiation source (1), a focusing element (4) configured such that the partial beams pass through it in such a way that the partial beams can be interfered with on the surface or in the volume of a substrate, preferably a flat and / or transparent substrate (5) in an interference area,wherein the beam splitter (2) is freely movable along its optical axis in the beam path (3), and wherein the beam splitter (2) is designed to split the incident laser beam emitted by the laser radiation source (1) into at least 3, preferably at least 4 partial beams, in particular 4 to 8, i.e. 4, 5, 6, 7, or 8 partial beams.

[0249] Particularly preferably, the beam splitter (2) is designed such that it divides the incident laser beam into an even multiple, ie 4, 6 or 8 partial beams, very particularly preferably 4 partial beams.

[0250] Alternatively or additionally, a beam splitter element (2) can be provided such that it comprises a first beam splitter and at least one further beam splitter arranged downstream of the first beam splitter, wherein the first beam splitter splits the incident laser beam into at least two partial beams and the further beam splitter is arranged in at least one beam path of a partial beam and splits this partial beam into at least two partial beams as it passes through.

[0251] For laser interference structuring of the substrate (5), preferably a flat and / or transparent substrate, the laser beam emitted by the laser radiation source is split into at least 3, preferably at least 4 partial beams by the beam splitter element (2). Only two-beam interference (i.e. structuring by means of interference of two partial beams) is known from the prior art. However, such two-beam interference only produces line structures on the substrate. The partial beams are subsequently deflected by the focusing element (4) such that they interfere in an interference region on the surface or inside a substrate (5), preferably a flat and / or transparent substrate.

[0252] This allows the creation of a two-dimensional, periodic dot structure with dimensions in the micrometer and submicrometer range, the structure period of which can be freely adjusted by displacing the beam splitter element (2) along its optical axis. Surface processing of a substrate (5), preferably a flat and / or transparent substrate, is possible.

[0253] According to a preferred embodiment, the beam splitter element is a single optical element, in particular a diffractive or refractive optical element, which is constructed such that the division of the incident laser beam is based on the optical properties of the beam splitter element. This advantageously ensures that a simple optical structure can be implemented compared to a multi-part beam splitter element consisting of several optical elements (e.g., mirrors, prisms, etc.). The desired beam splitting can be achieved without the need to calibrate or adjust the arrangement of several optical elements to one another. The mobility of the beam splitter element within the beam is also very easy to implement, since only a single optical element needs to be moved.In addition, the use of a one-piece beam splitter element results in fewer components that are susceptible to wear and tear and may need to be replaced.

[0254] One advantage of the device defined herein is that this device and the method that can be implemented with its aid eliminate the use of chemicals and their costly disposal when structuring substrates, particularly when creating a structure with improved heat transfer properties, especially with an increased heat transfer coefficient. Furthermore, substrate purification is also eliminated.

[0255] Furthermore, a wide variety of substrates, preferably flat and / or transparent substrates, in particular transparent materials, can be processed with the device. Since the process is not dependent on the refractive index or the adhesion of specific coating materials to the substrate, this process is more flexible than conventional chemical processes. Compared to conventional processes, such as WO 2019 / 166836 A1, the processing time using this process is significantly shorter, since the periodicity of the structures is ensured by the interference of the incident, at least three, preferably at least four, partial beams in an interference region, and does not arise from more time-consuming self-organization processes. Another advantage over conventional processes is that the shape (structural design; geometry) of the generated micro / nanostructures can be controlled.By adjusting the number of interfering (partial) beams, their polarization, and the process parameters, the geometry of the structures can be controlled, thereby specifically influencing the heat transfer properties, especially the heat transfer coefficient.

[0256] Furthermore, the stability of the dot structure created in this way should be mentioned, which is more durable than conventional coatings, since it cannot detach from the substrate to be coated over time and due to the material stresses caused by use.

[0257] If the structuring is performed in the volume, i.e., inside the substrate, preferably a flat and / or transparent substrate, especially in the transparent material, the resulting structuring (i.e., the dot structure of the structured substrate) is less sensitive to impact and abrasion than conventional coatings. The inventors have discovered that structuring (also referred to herein as texturing) inside the material (i.e., below the surface) does not necessarily produce anti-reflective properties. However, texturing inside the material is interesting for other applications, such as product protection, optical data storage, decoration, etc.

[0258] It is particularly advantageous that the structure of the device or the arrangement of the optical component disclosed herein enables substrates with very high structuring rates of up to 4.0 m 2 / min, especially in the range from 0.01 to 4.0 m 2 / min, particularly preferably in the range of 0.05 to 3.5 m 2 / min, most preferably in the range of 0.1 to 3.0 m 2 / min. This is ensured by the fact that the area in which the at least three partial beams are superimposed can be expanded through a preferred selection of optical elements, allowing a large area to be irradiated in a single processing step. In contrast to methods known to those skilled in the art, such as direct laser writing, no strong focusing is necessary to produce high-resolution features. USE

[0259] The process for producing a surface-structured substrate and the surface-structured substrate itself are suitable for use in the medical and laboratory technology sectors, where equipment must be provided with a stable, abrasion-resistant, and sterile marking to identify the manufacturer and batch, if necessary. When marking medical devices, the manufacturer faces the challenge of designing a marking that meets the requirements of a sterile environment. Markings created by applying additional materials, such as stickers or color prints, do not meet these requirements. A surface-structured substrate with a black marking offers the advantage of creating a permanent marking without the application of foreign matter such as color pigments or adhesives. Products processed in this way are therefore ideal for use in the medical and laboratory technology sectors.

[0260] The process for producing a surface-structured substrate and the surface-structured substrate itself are also suitable for use in logistics, consumer goods, and retail. By directly applying a barcode or a 2D code, such as a QR code, to a product, the product can be uniquely identified. Black marking as defined herein advantageously saves material and resources, as the use of stickers or additional packaging material, for example, is eliminated. This ensures the traceability of a product's supply chain, which also simplifies quality assurance. Product information can also be applied directly to the product, as well as markings to prevent product counterfeiting.

[0261] The method for producing a surface-structured substrate and the surface-structured substrate itself are particularly suitable for branding accessories, in particular accessories with metal surfaces. The black marking, as defined herein, can be used both to apply a marking and to process the surface to achieve a matting finish. The desired effect can preferably be adjusted by adjusting the overlap between two adjacent interference pixels. This allows visual accents to be created on the surface of the accessory. Brand logos, serial numbers, or a type designation of the (precious) metal used can also be applied in an abrasion-resistant manner. Varying the process parameters advantageously allows the appearance of the resulting marking to be specifically influenced.This makes it possible to create both a discreet marking that stands out only slightly from the base material and is therefore not perceived as disturbing by the viewer, as well as a clearly visible marking that, for example, allows the brand logo to stand out clearly.

[0262] The method for producing a surface-structured substrate and the surface-structured substrate itself are also suitable for use in the aerospace sector, with the resulting surface structuring offering the advantage of being resistant to extreme temperature conditions. Thus, it can be used both for marking components and for processing the exterior surfaces of a missile or aircraft. The use of a surface-structured substrate as defined herein advantageously leads to both a matting or blackening of an aircraft, which reduces its visibility by suppressing reflection and blending it into a dark background, and to altered aerodynamic properties, particularly with regard to air friction.The wetting properties of such a structured substrate also differ from those of an unstructured substrate, so that it can also be used advantageously to create anti-fogging and anti-icing properties.

[0263] The method for producing a surface-structured substrate and the surface-structured substrate itself are also suitable for use in the automotive industry. In addition to the already mentioned advantages in the area of ​​marking to identify vehicles or vehicle components for supply chain traceability and / or quality assurance, the appearance of a vehicle can also be influenced. In particular, the method defined herein can be used to mat the exterior and interior surfaces of a vehicle, advantageously avoiding the use of additional materials such as films or paints.

[0264] The method for producing a surface-structured substrate and the surface-structured substrate itself are also suitable for use in the field of optics and sensor technology. The method disclosed herein for producing a surface-structured substrate with a black marking region can advantageously be used to reduce stray light within an optical device such as a camera, a sensor, or a microscope, since the black marking region increases the absorption of incident light rays.

[0265] The present invention is explained in more detail with reference to the following figures and exemplary embodiments, without limiting the invention to these.

[0266] This shows

[0267] Fig. 1 : a section through a substrate with a periodic dot structure

[0268] Fig. 2: a section through a surface-structured substrate with a periodic dot structure

[0269] Fig. 3: a surface-structured substrate with a periodic structure, which is formed as a periodic line structure.

[0270] Fig. 4: A surface-structured substrate with line structures running in two directions to create two-dimensional surface irregularities

[0271] Fig. 5: The generation of cones using an auxiliary layer.

[0272] Fig. 6: a groove-shaped depression.

[0273] Fig. 7A: a schematic representation of an inverse cone.

[0274] Fig. 7B: a schematic representation of a cone-like depression with a circular base.

[0275] Fig. 7C: a schematic representation of a cone-like depression with an irregular base.

[0276] Fig. 8: a cumulative structure of the dot structure from a superposition of several interference pixels,

[0277] Fig. 9: a dot structure formed from the superposition of several first and second interference pixels,

[0278] Fig. 10: a schematic perspective view of a device according to the invention.

[0279] Fig. 11: a schematic perspective view of a device according to the invention, which contains a deflection element (6) for parallelizing the partial beams.

[0280] Fig. 12: a schematic perspective view of a device according to the invention, which contains a deflection element (7) for widening the angle of the partial beams to the optical axis of the beam path (3).

[0281] Fig. 13A: a schematic perspective view of a device according to the invention, which includes optical elements (6) with a planar, reflective surface that deflect the partial beams onto the focusing element (4). Fig. 13B: a schematic perspective view of a device according to the invention, which includes a galvo mirror (9) as an optical element for beam shaping, which allows for stationary positioning of the substrate to be structured during the structuring process.

[0282] Fig. 14: a schematic perspective view of a device according to the invention, wherein the device contains a polarization element (8) which shifts the phase profile of the partial beams relative to each other, wherein

[0283] A) the beam splitter element (2) is positioned in the beam path (3) close to the laser radiation source (1).

[0284] B) the beam splitter element (2) is positioned in the beam path (3) close to the deflection element (7).

[0285] Fig. 15: a schematic view of the interference pixels with width D resulting on the surface or inside the substrate, and the distribution of the individual interference pixels on the surface or inside the substrate, wherein the interference pixels are shifted relative to each other with the pixel density Pd.

[0286] Fig. 16: a schematic perspective view of the structured substrate (5) with the generated periodic dot structures, consisting of inverse cones, with dimensions in the micro- and submicrometer range, and symbolically the transmission of incident electromagnetic waves with wavelengths greater than the interference period of the generated structures, as well as the diffraction of incident electromagnetic waves with wavelengths in the range or smaller of the generated structures.

[0287] Fig. 17: a schematic perspective view of a device according to the invention, which contains as optical element a galvo mirror (9) with a planar, reflective surface, which deflects the partial beams onto the focusing element (4), and a polygon wheel (91).

[0288] Fig. 18: a graphical representation of the diffraction angle of incident light versus the wavelength of the incident light for structured substrates with three different feature sizes.

[0289] Fig. 19: a schematic perspective view of the structured substrate (5) with the generated periodic dot structures consisting of inverse cones with dimensions in the micrometer range, on which a periodic wave structure in the submicrometer range is superimposed.

[0290] Fig. 20: a schematic

[0291] A) Top view and B) a cross-sectional view of a quasi-periodic wave structure in the submicrometer range.

[0292] Fig. 21 a schematic representation of the reduction of reflection due to the trapping effect in inverse cones

[0293] Fig. 22: an illustration of the reduced gloss factor using a structured substrate

[0294] Fig. 23: a graphical representation of the structure depth and gloss factor as a function of the pulse overlap of the interference pixels resulting on the surface or inside the substrate

[0295] Fig. 24: a graphical representation of the structure depth as a function of the spatial extent of the interference pixel along its diameter

[0296] Fig. 25: a graphical representation of the oxygen content and gloss factor as a function of the pulse overlap of the interference pixels resulting on the surface or inside the substrate

[0297] Fig. 26: a schematic view of the interference pixels with width D resulting on the surface or inside the substrate, and the distribution of the individual interference pixels on the surface or inside the substrate, wherein the interference pixels are shifted relative to each other with the pixel density Pd, whereby a global unstructured area results between the individual interference pixels

[0298] Fig. 1 shows a perspective view of a portion of a substrate 5. The substrate 5 has a first outer surface 32. The first outer surface 32 typically faces the environment, i.e., in particular, the air, water, or another fluid.

[0299] The first outer surface 32 is formed from a structured region 28 and an unstructured region 29. The structured region 28 shown here is formed from a periodic structure of surface irregularities 34. According to an alternative embodiment, the structured region 28 can also be formed from a superposition of several periodic structures, so that the superimposed structure, also referred to as a global structure, or in the case of point structures as a global point structure, does not have to be periodic, in particular not fully periodic. The surface irregularities 34 are formed here as inverse pegs 14, wherein the periodic structure is a periodic point structure. A section of a surface-structured substrate 5, comprising a base layer 37 and a cover layer 35 adjacent to the base layer 37, is shown in a perspective view in Fig. 2.

[0300] Here, too, the first outer surface 32 of the substrate 5 is formed from a structured region 28 and an unstructured region 29. In the variant shown here, the entirety of the inverse pins 14 forms the structured region 28.

[0301] Fig. 3 shows a surface-structured substrate 5 with a periodic structure, which is formed as a periodic line structure. Here, the surface irregularities 34 arranged on the first outer surface 32 of the cover layer 35 of the substrate 5, from which the structured region 28 is formed, are formed as groove-shaped depressions 36 with a large extent in a first dimension Dim1. The extent of the groove-shaped depressions 36 in a second dimension Dim2 and in a third dimension Dim3 is significantly smaller.

[0302] The periodicity of the structure results from the repetition of the groove-shaped depressions 36 with equal spacing, so that the interference period p, in particular the first interference period p1, extends from a certain point of the groove-shaped depression 36, for example the deepest point, to the point corresponding to this point of the groove-shaped depression 36 arranged next to it.

[0303] Fig. 4 shows a substrate 5 in which first and second groove-shaped (linear) depressions 36A, 36B are represented as surface irregularities 34, the first dimensions Dim1A and Dim1B of which extend in different directions. As a result, the remaining unstructured regions 29 form two-dimensional changes in the surface. The structured region is formed here by the groove-shaped depressions 36A, 36B. The different directions Dim1A and Dim1B enclose an orthogonal angle.

[0304] In Fig. 5, cones 43 are created on a substrate 5 by depositing an auxiliary layer 31 on a transparent base layer 37. A laser beam 3 is guided through the base layer 37, which is transparent to the wavelength of the laser light, to the auxiliary layer 31. The surface of the base layer 37 facing the auxiliary layer 31 is scanned, creating cones 43. The auxiliary layer 31 is then removed, leaving only the cones 43 made of the material of the auxiliary layer 31. The cones form the cover layer 35.

[0305] Fig. 6 schematically shows a surface irregularity 34 formed as a groove-shaped depression 36. The deepest line in such a symmetrical structure is the center line 39.

[0306] The area where the groove-shaped depression 36 intersects the corresponding surface is referred to as the base area 40 of the surface irregularity. The base area 40 then forms the section of the structured area of ​​the surface that can be assigned to this surface irregularity. The side surfaces 41 are smooth here. However, a groove-shaped depression can also be overlaid with a quasi-periodic line structure. In this embodiment, the width b of the groove-shaped depression 36 is smaller than the structure depth x.

[0307] Fig. 7A shows a schematic representation of an inverted stud 14 produced by a laser interference method, which has a structure depth x. The base surface 40 of the inverted stud 14 is circular in shape with a diameter d. The side surfaces 41 are smooth.

[0308] A schematic representation of a peg-like depression 42, such as can be generated, for example, by means of an etching process using a mask with circular openings (not shown here), is shown in Fig. 7B. Although the illustrated base surface 40 is circular, the side surfaces 41 are irregularly shaped.

[0309] Fig. 7C shows a schematic representation of a peg-like depression 42 with an irregular base surface 40 and an irregular, completely variable side surface 41. Such a depression is generated, for example, during etching without a mask.

[0310] Fig. 8 visualizes the cumulative structure of the dot structure from a superposition of several interference pixels (10, 11, 12, 13). Each interference pixel (10, 11, 12, 13) consists of several inverse cones (14) introduced into the substrate by laser interference structuring.

[0311] Partial image (A) shows the first interference pixel (10), which has several inverse cones (14, 14.1). Partial image (B) visualizes an overlay of the first interference pixel (10) and the second interference pixel (11), with this overlay consisting of inverse cones (14.1) of the first interference pixel (10) and inverse cones (14.2) of the second interference pixel (11).

[0312] There is an offset (15) between the first interference pixel (10) and the second interference pixel (11), whereby the inverse cones (14.2) of the second interference pixel (11) are shifted by this offset (15) relative to the inverse cones (14.1) of the first interference pixel (10).

[0313] Partial figure (C) visualizes an overlay in which a third interference pixel (12) is additionally superimposed on the first two interference pixels (10, 11). The superimposed structure in partial image (C) thus has inverse cones (14.1) of the first interference pixel (10), inverse cones (14.2) of the second interference pixel (11), and inverse cones (14.3) of the third interference pixel (12). In this exemplary embodiment, the third interference pixel (12) is shifted relative to the second interference pixel (11) in the same spatial direction along the x-axis as the second interference pixel (11) is shifted relative to the first interference pixel (10).

[0314] Partial image (D) shows an overlay in which a fourth interference pixel (13) is also superimposed, which is shifted in a different spatial direction along the y-axis compared to the third interference pixel (12). Thus, the section in partial image (D) has a dot structure consisting of a superposition of four interference pixels (10, 11, 12, 13).

[0315] The graphs arranged below the interference pixels (10, 11, 12, 13) serve to visualize the periodic structures within an interference pixel (10, 11, 12, 13). Due to the formation of the interference pixels (10, 11, 12, 13) via the process of laser interference structuring, i.e., according to the interference pattern of the laser (partial beams), each individual interference pixel (10, 11, 12, 13), which was formed during an illumination or irradiation process within a selected pulse duration, exhibits a periodic arrangement of the inverse cones (14). The distance between the inverse cones (14.1) of the first interference pixel (10), which results from the distance between the intensity maxima of the interference image generating the first interference pixel (10), represents the interference period (p1). The intensity corresponds to the intensity in the interference pattern of the laser (partial) beams required to generate the inverse cones (14.1).Thus, the distance between the intensity maxima of the interference image corresponds to the interference period (pi). The second interference pixel (11) has a second interference period (P2). Fig. 9 shows a dot structure (16) formed from the superposition of several first interference pixels (10) with a first interference period (pi) and several second interference pixels (11) with a second interference period (P2). The first interference pixels (10) have inverse cones (14.1), which are shown here with a vertical pattern fill. The second interference pixels (11) have inverse cones (14.2), which are shown with a horizontal pattern fill. The interference period (pi) of the first interference pixel (10) is smaller than the second interference period (p2) of the second interference pixel (11).

[0316] In an optional setting of the interference pixels (10, 11) such that the number of inverse cones (14.1, 14.2) within the interference pixels (10, 11) is identical, the area of ​​the interference pixels (10, 11) varies, which is visualized here by the circles. One of the first interference pixels (10) is schematically represented here by all inverse cones (14.1) with vertical pattern filling within the smaller circle. One of the second interference pixels is, in turn, visualized by the inverse cones (14.2), which are represented with a horizontal pattern structuring, within the larger circle.

[0317] The plurality of first interference pixels (10) are arranged adjacently and repetitively offset from one another, thereby forming a pattern with the interference period (p1). Furthermore, the plurality of second interference pixels (11) are arranged adjacently and repetitively offset from one another, thereby forming a pattern with the second interference period (P2) that differs from the first interference period (p1).

[0318] The graph located below the dot structure (16) visualizes the arrangement of the inverse cones (14.1, 14.2) along a line through the dot structure (16). The intensity maxima correspond to the center of the inverse cones (14.1, 14.2). As in Fig. 8, this graph serves to illustrate the principle. The intensity corresponds to the intensity in the interference pattern of the laser beams (partial) required to generate the inverse cones (14.1, 14.2).

[0319] Fig. 10 visualizes, in a first embodiment, the device according to the invention, comprising a laser radiation source (1) for emitting a laser beam. Arranged in the beam path (3) of the laser beam behind the laser radiation source (1) is a beam splitter element (2), which is movably arranged in the beam path (3). Arranged in the beam path (3) of the laser beam behind the beam splitter element (2) is a focusing element (4). Arranged in the beam path (3) of the laser beam behind the focusing element (4) is a holding device on which a substrate (5), preferably a flat and / or transparent substrate, is mounted.

[0320] In this embodiment, the laser radiation source (1) emits a pulsed laser beam. The laser radiation source is a UV laser with a wavelength of 355 nm and a pulse duration of 12 ps. The radiation profile of the laser radiation source in this embodiment corresponds to a top-hat profile.

[0321] In this embodiment, the beam splitter element (2) corresponds to a diffractive beam splitter element. A diffractive beam splitter element here is a beam splitter element that contains micro- or nanostructures. The beam splitter element (2) divides the laser beam into four partial beams.

[0322] In this embodiment, the focusing element (4) corresponds to a refractive, spherical lens that directs the essentially parallel partial beams onto the substrate (5), preferably a flat and / or transparent substrate, such that they interfere there in an interference region. The interference angle in this embodiment corresponds to 27.2°, resulting in an interference period of 550 nm for the periodic dot structure with the same polarization state.

[0323] According to this embodiment, the planar substrate is irradiated once, resulting in a processing time per structural unit, ie per interference pixel, of 12 ps.

[0324] The substrate (5), preferably a flat and / or transparent substrate, is a glass, very specifically a quartz glass, which is mounted on a holding device so that it is movable in the xy plane, perpendicular to the beam path of the laser beam emitted by the laser radiation source (1).

[0325] Fig. 11 visualizes in a further embodiment the device as described in Fig. 10, additionally comprising a deflection element (6) which is located in the beam path (3) of the laser after the beam splitter element (2) and the focusing element (4).

[0326] In this embodiment, the deflection element is a conventional, refractive, convex lens. The partial beams impinge on the deflection element (6) in such a way that, after passing through the deflection element, they run essentially parallel to each other. This allows the point at which the partial beams interfere on the surface or inside the substrate to be adjusted.

[0327] Fig. 12 illustrates a further embodiment of a device based on the structure shown in Fig. 10 and Fig. 11. This structure additionally comprises a further deflection element (7), which is arranged in the beam path (3) of the laser between the beam splitter element (2) and the deflection element (6).

[0328] In this embodiment, the additional deflection element (7) is a conventional, refractive, concave lens. The partial beams impinge on the additional deflection element in such a way that their angle to the optical axis of the beam path is widened. This allows the interference angle at which the partial beams interfere on the surface or inside the substrate, preferably a flat and / or transparent substrate, to be changed.

[0329] In this embodiment, all optical elements except for the beam splitter element (2) are fixed along the optical axis of the beam path (3). The interference angle of the partial beams on the substrate is adjusted by moving the beam splitter element (2) along the optical axis of the beam path.

[0330] Fig. 13A shows, in a further embodiment, a device as in Fig. 12, comprising the optical elements (6) with a planar, reflective surface, which are arranged such that they deflect the partial beams onto the focusing element (4).

[0331] In this embodiment, the at least three partial beams are directed onto the substrate by shifting the optical elements (6) at a preferred angle. This eliminates the need for a deflection element in the form of a lens (reference numeral (6) in Fig. 12).

[0332] Fig. 13 B shows a schematic perspective view of a device according to the invention, which comprises a galvo mirror (9) as an optical element for beam shaping, which allows a fixed positioning of the substrate 5 to be structured during the structuring process.

[0333] Fig. 14 illustrates a further embodiment of a device as in Fig. 10, additionally comprising a polarization element (8) for each partial beam, which is arranged in the beam path (3) of the laser beam between the deflection element (6) and the focusing element (4). The polarization element is arranged in such a way that it changes the polarization of the individual partial beams relative to one another, resulting in a change in the interference pattern.

[0334] This design is shown in two different configurations. In Fig. 14A, the beam splitter element (2) is positioned in the beam path (3) close to the laser radiation source (1). In Fig. 14B, the beam splitter element (2) is positioned in the beam path (3) close to the deflection element (7). In this way, the interference pattern of the interfering partial beams on the surface of the substrate (5) can be continuously adjusted without having to move the other optical elements in the structure or the substrate itself.

[0335] Additionally, it would also be conceivable for the arrangement to include an additional optical element for beam shaping, which is arranged downstream of the laser radiation source (1) in the beam path (3). In this embodiment, the radiation profile of the laser radiation source corresponds to a Gaussian profile. The optical element for beam shaping converts this profile into a top-hat profile.

[0336] Fig. 15 contains a schematic view of the interference pixels with the width D resulting on the surface or inside the substrate, and the distribution of the individual interference pixels on the surface or inside the substrate, wherein the interference pixels are shifted from each other with the pixel density Pd.

[0337] In this embodiment, the pixel density Pd is smaller than the width of an interference pixel, D. As a result, a planar homogeneous periodic dot structure can be generated on the surface or inside a substrate, preferably a planar and / or transparent substrate, by moving the substrate (5) by means of a pulsed laser beam.

[0338] Preferably, the successively applied interference pixels are arranged next to one another. In this embodiment, there is an overlap between two adjacent interference pixels. Due to the multiple irradiation, self-organization processes within the structured area, i.e., within the inverse cones 14, are preferentially stimulated. This allows a hierarchical structure to be efficiently created.

[0339] Fig. 16 visualizes the structured substrate (5) produced by the inventive method with the generated periodic dot structures consisting of inverse cones with dimensions in the micrometer and submicrometer range. It also symbolically illustrates the transmission of incident electromagnetic waves with wavelengths greater than the interference period of the generated structures, as well as the diffraction of incident electromagnetic waves with wavelengths in the range of or smaller than the generated structures.

[0340] Fig. 17 shows, in a further embodiment, a device as in Fig. 13B, comprising the optical element (91) with a planar, reflective surface, which is a polygon wheel configured to rotate about a marked axis. The incident partial beams are deflected such that they impinge on a galvo mirror (9), which directs the beams onto the substrate via a focusing element (4). The rotation of the polygon wheel causes the point at which the beams are focused on the substrate to move along a line during the exposure process. The partial beams thus scan the substrate, which leads to an increased process speed.

[0341] Fig. 18 graphically illustrates the transmission and diffraction capabilities of a structured substrate as a function of the structure size. The diffraction angle of light is shown as a function of its wavelength for structures with three different structure sizes. If the wavelength of the incident light is longer than the structure size, the light is completely transmitted. At wavelengths in the range of the structure size or smaller, diffraction occurs. The diffraction angles can be seen in the graph.

[0342] Fig. 19 visualizes the structured substrate (5) produced by the inventive method with the generated periodic dot structures consisting of inverse cones with dimensions in the micrometer range. Superimposed on this periodic dot structure in the micrometer range is a periodic wave structure in the submicrometer range, which can also be produced in a single production step by the inventive method described herein.

[0343] Fig. 20A visualizes a quasi-periodic wave structure (19) in a plan view and Fig. 20B in a sectional view, as it has a structured substrate which can be produced by a method disclosed herein, in particular by multiple irradiation or by single irradiation with high intensity. The sectional view of Fig. 11B represents a cross-section through the structure shown in Fig. 11A approximately along the section line AA. Self-organization processes occurring in the materials lead to the formation of wave-like structures with wave crests (20) and wave troughs (21) within such an irradiated area. The resulting structures generally exhibit a certain periodicity, although defects (22), i.e., irregularities, also occur.Thus, in contrast to a truly periodic structure, such a structure exhibits both deviations in the structural dimensions, particularly in the distances between the wave crests and the wave troughs, as well as defects, so that the generated wave structure is not homogeneous.

[0344] A schematic cross-sectional view of a structured substrate 5 is shown in Fig. 21 to visualize the reduction in reflection due to the trapping effect. A cover layer 35 is shown facing upwards. A base layer 37 is shown below the cover layer 35.

[0345] Inverse cones 14 are arranged on the substrate, with the sectional view lying straight in a row of inverse cones 14. Light 44 incident on the inverse cones 14 also partially strikes an interface point 45 arranged within an inverse cone 14. A portion of the light 44 is transmitted at this interface point 45 through the interface into the interior of the cover layer 35. A further portion of the light 44 is, however, reflected and strikes another interface point 45 arranged within an inverse cone 14. There, too, a portion of the light 44 is transmitted through the interface between the air and the cover layer, and a smaller portion is reflected. In this view, this reflected portion also reaches another interface point 45, where again a portion of the light 44 is transmitted. As a result, the total amount of light 44 transmitted through the interface can be determined.1 can be significantly increased compared to a surface without inverse cones 14.

[0346] Fig. 22 shows, in a further embodiment, an image of a structured substrate (5), which in this example is a flat substrate made of stainless steel. On the substrate there are regions (28) structured using the method disclosed herein, wherein the structuring produced is a black marking and wherein this black marking is produced by applying interference pixels (10, 11, 12, 13) by means of direct laser interference structuring. In this case, the interference pixels in the regions of the structuring, in particular the black marking, have an area in which neighboring interference pixels overlap, referred to herein as an overlap. The gloss factor of the structured regions can be seen from this image. A larger overlap leads to a reduction in the gloss factor. Fig.Figure 23 shows a graphical representation of the relationship between the overlap between two adjacent interference pixels (10, 11, 12, 13) and the gloss factor as well as the structure depth of a structured substrate (5). It is clear that with a larger overlap between two adjacent interference pixels, the gloss factor decreases, while the structure depth at the surface of the generated structure increases.

[0347] Fig. 24 shows, in a further embodiment, the distribution of the structure depth as a function of the spatial extent of the first interference pixel (10) along its diameter. In this embodiment, the laser radiation source (1) is a laser radiation source with a Gaussian profile. The optical structure in this embodiment does not include any further optical element for beam shaping. It is evident that the structure depth varies within an interference pixel in this case, in particular that the structure depth decreases towards the edges of the interference pixel.

[0348] Fig. 25 graphically illustrates the relationship between the overlap between two adjacent interference pixels (10, 11, 12, 13) and the gloss factor as well as the oxygen content at the surface of a structured substrate (5). It is clear that with a larger overlap between two adjacent interference pixels, the gloss factor decreases, while the oxygen content at the surface of the resulting structure increases.

[0349] Fig. 26A contains a schematic view of the interference pixels with the width D resulting on the surface or inside the substrate, and the distribution of the individual interference pixels on the surface or inside the substrate, wherein the interference pixels are shifted from each other with the pixel density Pd.

[0350] In this embodiment, the pixel density Pd is greater than the width of an interference pixel, D. This allows for a planar structuring of the substrate surface by moving the substrate (5) using a pulsed laser beam, which omits certain areas of the substrate surface. This results in a globally unstructured area in which the properties of the substrate remain unchanged compared to the unstructured substrate.

[0351] Fig. 26B contains a schematic view of the interference pixels with the width D resulting on the surface or inside the substrate, and the distribution of the individual interference pixels on the surface or inside the substrate, wherein the interference pixels are shifted from each other with the pixel density Pd, and wherein a first and a second interference pixel have been applied on the surface.

[0352] In this embodiment, the first and second interference pixels are arranged with an offset from each other that is smaller than the diameter of the interference pixels. This results in an overlap of the two interference pixels in one region. In this embodiment, the first interference pixel and the second interference pixel are identical.

[0353] In this embodiment, the pixel density Pd is greater than the width of an interference pixel, D. This allows for a planar structuring of the substrate surface by moving the substrate (5) using a pulsed laser beam, which omits certain areas of the substrate surface. This results in a globally unstructured area in which the properties of the substrate remain unchanged compared to the unstructured substrate.

[0354] Fig. 26C shows, in a further embodiment, a structured substrate consisting of a structured, an unstructured, and a global unstructured region. The structuring on the surface of the substrate is carried out in such a way that targeted recesses are created, which allow the formation of a pattern.

[0355] QR codes or logos, for example, can preferably be applied in this way.

[0356] LIST OF REFERENCE SYMBOLS

[0357] 1 laser radiation source

[0358] 2 beam splitter element

[0359] 3 Beam path, laser beam

[0360] 4 Focusing element

[0361] 5 Substrat

[0362] 6 additional deflection element

[0363] 7 Deflection element

[0364] 8 Polarization element

[0365] 9 Focusing mirror or galvo mirror

[0366] 91 Polygon wheel

[0367] 10 first interference pixel

[0368] 11 second interference pixel

[0369] 12 third interference pixel

[0370] 13 fourth interference pixel

[0371] 14 inverse cones

[0372] 14.1 Inverse cones of the first interference pixel

[0373] 14.2 Inverse cones of the second interference pixel

[0374] 14.3 Inverse cones of the third interference pixel

[0375] 14.4 inverse cones of the fourth interference pixel

[0376] 15 Offset

[0377] 16 point structure

[0378] Pi first interference period

[0379] P2 second interference period

[0380] 19 quasi-periodic wave structure

[0381] 20 Wave Mountain

[0382] 21 wave trough

[0383] 22 Defect

[0384] 23 Water contact angle

[0385] 24 drops of water

[0386] 25 Gas phase

[0387] 26 Tangent

[0388] AA cutting line

[0389] 28 structured area

[0390] 29 unstructured area

[0391] 30 Surface-structured component 31 Auxiliary layer

[0392] 32 First outer surface

[0393] 33 Second outer surface

[0394] 34 Surface unevenness

[0395] 35 Top layer

[0396] 36 groove-shaped depressions

[0397] 36A First groove-shaped depressions

[0398] 36B Second groove-shaped depressions

[0399] 37 Base layer

[0400] 39 Center line

[0401] 40 floor space

[0402] 41 side surface

[0403] 42 Cone-like depression

[0404] 43 cones

[0405] 44 Global unstructured area

[0406] Dim1 first dimension

[0407] Dim2 second dimension

[0408] Dim3 third dimension

[0409] Dim1A first dimension of a first groove-shaped depression

[0410] Dim1 B first dimension of a second groove-shaped depression

[0411] D Width of the interference pixel

[0412] Pd pixel density d diameter of an inverse cone b width x structure depth

Claims

PATENT CLAIMS 1. A surface-structured substrate (5), wherein the surface-structured substrate (5) has at least one first outer surface (32) with a black marking region, wherein the black marking region is formed by a structured region (28) and an unstructured region (29), wherein the structured region (28) has a first interference pixel (10), wherein the first interference pixel (10) is formed from a first periodic structure of at least three surface irregularities (34), wherein the distance between two adjacent surface irregularities (34) is a first interference period (pi), wherein the first interference period (pi) is in the range from 50 nm to 200 pm, preferably from 5 pm to 45 pm, and wherein the structured region (28) further has a plurality of mutually offset interference pixels each comprising a periodic structure of at least three surface irregularities (34),wherein at least 50% of the mutually offset interference pixels have an overlap of at least 95%, preferably of at least 97%., 2. Surface-structured substrate (5) according to claim 1, wherein the black marking area is formed with a gloss factor of less than 10.

3. Surface-structured substrate (5) according to claim 1 or 2, wherein the gloss contrast between the surface of the originally unstructured region of the substrate and the surface with the structured region is greater than 0.

85.

4. Surface-structured substrate (5) according to one of claims 1 to 3, wherein the structured region is divided into at least two sub-regions, wherein the respective sub-regions are characterized in that the shape of the surface irregularities, the structural depth of the surface irregularities and / or the spacing of the surface irregularities differ from one another.

5. Surface-structured substrate (5) according to one of claims 1 to 4, wherein the first outer surface (32) is formed as a component of a cover layer (35) and wherein the cover layer (35) is formed adjacent to a base layer (37).

6. Surface-structured substrate (5) according to claim 5, wherein the base layer (37) comprises a transparent material, preferably glass, or is formed from a transparent material, preferably glass.

7. Surface-structured substrate (5) according to one of claims 1 to 6, wherein the material of the surface-structured substrate (5) and / or the cover layer (35) comprises, preferably consists of, at least one metal, preferably copper and / or aluminum, an alloy and / or a semiconductor, preferably silicon.

8. Surface-structured substrate (5) according to claim 7, wherein in the structured region the oxygen content is in the range of at least 8 to 40 wt.%, preferably in the range of at least 10 to 30 wt.%, particularly preferably in the range of at least 15 to 30 wt.%.

9. Surface-structured substrate (5) according to one of claims 1 to 8, wherein the material of the surface-structured substrate (5) and / or the cover layer (35) has a melting point of less than 1,400 °C, preferably less than 1,200 °C, particularly preferably less than 1,100 °C.

10. Surface-structured substrate (5) according to one of claims 1 to 9, wherein the first interference pixel (10) has a periodic grating of at least three cones (43) or inverse cones (14).

11. Surface-structured substrate (5) according to one of claims 1 to 10, wherein the first interference pixel (10) is formed of a first periodic line structure made up of at least three groove-shaped depressions (36) or groove-shaped elevations arranged next to one another, running parallel to one another and arranged equidistantly.

12. Surface-structured substrate (5) according to one of claims 1 to 11, wherein the structured region (28) further comprises a second periodic structure with a second interference period (P2) in the micro- or submicro-range, which is formed as a periodic dot structure or as a periodic line structure.

13. Surface-structured substrate (5) according to one of claims 1 to 12, wherein the structure depth of the surface irregularities (34) of the first interference pixel (10) is in the range from 0.3 pm to 60 pm, preferably in the range from 0.5 pm to 40 pm.

14. Surface-structured substrate (5) according to one of claims 1 to 13, wherein the surface irregularities (34) have side surfaces (41) with a smooth surface.

15. A method for producing a surface-structured substrate (5) according to one of claims 1 to 14, comprising the following steps: a) providing a substrate (5) to be structured, wherein the substrate (5) to be structured has an interface, wherein the interface is formed as a direct contact surface between the surface of the substrate (5) to be structured and a medium adjacent thereto, wherein the substrate (5) to be structured or the medium adjacent thereto comprises a material with a thermal conductivity of at least 20 W / (m K), b) applying a structured region to the surface of the substrate (5) to be structured, thereby creating a black marking region on the surface to be structured, wherein the structured region (28) has at least one first interference pixel (10) with a first interference period (pi),wherein the first interference pixel (10) is formed from a first periodic structure of at least three surface irregularities (34), wherein the distance between two adjacent surface irregularities (34) is a first interference period (pi), wherein the structured region (28) further comprises a plurality of further interference pixels arranged offset from one another, wherein the structured region (28) is formed by superimposed application of the first interference pixels (10) on a surface or in the volume within the interface of the substrate (5), wherein the first interference pixels (10) have an overlap of at least 90%, preferably of at least 95%.

16. The method according to claim 15, wherein the substrate (5) to be structured is designed as a base layer (37) and the medium adjacent to the substrate (5) to be structured is designed as an auxiliary layer (31) with a material having a thermal conductivity of at least 20 W / (m K).

17. The method according to claim 15 or 16, wherein the auxiliary layer is removed from the base layer (37) following step b), whereby a cover layer (35) adjacent to the base layer (37) remains.

18. The method according to claim 15 or 17, wherein the base layer (37) comprises a transparent material, preferably glass, or is formed from a transparent material, preferably glass.

19. The method according to any one of claims 15 to 18, wherein the material having a thermal conductivity of at least 20 W / (m K) comprises or is formed from at least one metal, preferably copper and / or aluminum, at least one alloy or at least one semiconductor, preferably silicon.

20. The method according to any one of claims 15 to 19, wherein the first interference period (pi) is formed in the range from 50 nm to 200 pm, preferably from 1 pm to 45 pm.

21. The method according to one of claims 15 to 20, wherein the application according to step b) is carried out by means of a laser interference method, wherein partial beams are preferably generated by means of a beam splitter element (2) and the interference period (p) of an interference pixel, preferably the first interference period (pi) of the first interference pixel (10), is continuously variable by means of a displacement of the beam splitter element (2). is adjusted, wherein preferably the further optical elements are fixed in their spatial arrangement.

22. Method according to one of claims 15 to 21, wherein the periodic structure is first produced on a negative mold by means of a laser interference method and is applied to the surface of the substrate (5) to be structured by means of the negative mold.

23. The method according to any one of claims 15 to 22, wherein the periodic structure within an interference pixel is generated by applying a single laser pulse by means of single irradiation.

24. Method according to one of claims 15 to 23, wherein a hierarchical structure with a dot structure and / or line structure arranged in the depressions is produced by means of multiple irradiation of an interference pixel with identical process parameters.

25. Method according to one of claims 15 to 24, wherein a periodic line and / or dot structure superimposed on the first periodic structure is generated with varied method parameters.

26. The method according to any one of claims 15 to 25, wherein the laser pulse duration is in the range of 50 fs to 100 ns, preferably in the range of 500 fs to 50 ns, preferably in the range of 800 fs - 20 ns, particularly preferably in the range of 1 ps to 10 ns.

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