Substrate having surface bounded by microstructures and / or nanostructures

Abstract

A substrate having at least one surface that is bounded by microstructures and / or nanostructures and having a filling mass within the bounded surface, and the filling mass forms on or on top of the boundary an apparent static contact angle of ≥ 30°, preferably ≥ 35°, more preferably ≥ 40° and particularly preferably ≥ 42°.

Description

[0001] Substrate with a surface defined by microstructures and / or nanostructures

[0002] The present invention relates to a substrate having at least one surface defined by microstructures and / or nanostructures and a filler material within the defined surface, wherein the filler material forms an apparent static contact angle of > 30° at or on the boundary of the surface. The invention further relates to the use of microstructures and / or nanostructures for limiting the flow of a filler material, as well as to a method for producing a substrate according to the invention.

[0003] Many applications face the problem that fillers, such as paints, adhesives, and potting compounds, spread uncontrollably after application to substrates, sometimes covering areas that are not intended to be wetted. At the same time, the processes for controlling filler spread should be laterally resolved, i.e., they can be applied locally and do not require mechanical and / or wet-chemical operations. "Cold" processes are preferable to minimize thermal input into the environment. Two specific application scenarios will illustrate this need:

[0004] I. The growing number of electronic components and their use, e.g., in household appliances, motor vehicles, and aircraft, is leading to increasing demands regarding long-term stability and functional reliability. For many applications, this functionality must be ensured over long periods of time, even under harsh conditions. Components to be protected must be encased in a polymer by encapsulation or the application of protective coatings to protect them from the ambient conditions and thus ensure their reliability. For reasons of cost-effectiveness or recycling or repairability, only individual areas of circuit boards need to be protected, depending on the application.In these cases, there is a need to enable local encapsulation / sealing and to produce this – with increasing spatial resolution as microelectronics miniaturization progresses – while simultaneously keeping mechanical, thermal and media input as low as possible.

[0005] II. When bonding optical elements such as plastic lenses, e.g. made of polycarbonate (PC) or polymethyl methacrylate (PMMA), the spread of the adhesive must be controlled or restricted. If these are to be bonded, the properties of the lens structure and surface must not be changed by the pretreatment. For example, in the case of circumferentially bonded plastic lenses, only the outer adhesive surface may be treated. Any changes to the optically relevant surfaces must be prevented. It must also be ensured that the adhesive does not get onto the lens. If the spread of the adhesive is not restricted, this may impair the optically relevant surfaces. For sensitive plastic lenses, the spread of the adhesive should be limited laterally, if possible, with high resolution and without significant mechanical, chemical or thermal influences.

[0006] There are no general approaches to controlling the spread of paints, adhesives, and encapsulants. For this reason, a state-of-the-art solution is used for the above-mentioned specific first application:

[0007] The two-stage "Dam & Fill" or "Frame & Fill" process is a method for encapsulating semiconductor chips with their associated connections, primarily in "chip-on-board" applications on printed circuit boards, and is classified as "glob-top" technology. In contrast to the single-stage process, in which running is fundamentally avoided by using higher-viscosity adhesives, the two-stage process first uses a high-viscosity adhesive to create a border, a so-called dam ('dam') - usually by applying several layers of adhesive - which encloses the electronic component. The purpose of this dam is to prevent the actual encapsulating compound from leaking or flowing away and to prevent contamination of surrounding electronic areas after curing. In a second step, the encapsulating compound ('fill') is applied to the interior.The advantage here is that the encapsulation material can be designed to be so flowable that even the thinnest wires (~15 pm) are surrounded by bubble-free flow at the smallest contact pitch (cf. Ardebili, H.: Encapsulation Technologies for Electronic Applications, 2nd edition, Elsevier 2019).

[0008] The problem with the described method is that a significant amount of material is required for the dam, and the entire process is costly and time-consuming. Accordingly, there is a significant need to find a solution that is as general as possible, even for small-area flow restrictions of fill materials. This approach should ideally involve minimal material expenditure, be as time-consuming as possible, and, even more preferably, not introduce significant energy into the substrate on which the restriction is to be installed.

[0009] According to the invention, this object is achieved by a substrate having at least one surface delimited by means of microstructures and / or nanostructures and a filling compound within the delimited surface, wherein the filling compound forms an apparent static contact angle of > 20°, preferably > 30°, more preferably > 35°, even more preferably > 40° and particularly preferably > 42° at or on the boundary of the surface.

[0010] Microstructures in the sense of this text are three-dimensional structures that have a size in the range of 0.5 - 500 pm in at least one spatial dimension.

[0011] Nanostructures in the sense of this text are three-dimensional structures that have an extension of 10 - < 500 nm in at least one spatial direction.

[0012] Microstructures or nanostructures within the meaning of this text are created from the base substrate itself and are characterized by depressions and / or elevations in the specified size. Possible characteristics of the micro- and / or nanostructures are described in: https: / / patentimages.storage.googleapis.eom / 07 / 0d / d6 / e6b3ad2c3da3f0 / DE10239071A1 .pdf "The elevations / depressions can be regularly or irregularly arranged or fractal in nature. Surface structures with irregularly arranged substructures, which in turn have a regular arrangement, are also suitable. Examples of regular arrangements are waffle pattern structures (isolated depressions in a flat surface), mountain-valley structures (= isolated elevations and isolated depressions with saddle surfaces between them, often referred to as mountain-valley structures), columns and spikes (isolated elevations from a flat base structure, which, for example,"Fractal surfaces (which can be pyramidal, cuboid, irregular, or cylindrical) and stripes (= band-like elevations from a flat surface, or linear depressions in a flat surface). Such surface structures are known and described, for example, by Marzolin et al., Advanced Materials 1998, 10, pp. 571-574, Thin Solid Film 315, 1998, pp. 9-12. Examples of surfaces with irregularly arranged elevations / depressions are structures that can be obtained, for example, by fixing particulate materials to otherwise flat surfaces. Fractal surface structures and their production are described, for example, by Shibuichi et al., J. Phys. Chem. 1996, pp. 19512-19517. Examples of surfaces with irregularly arranged substructures, which in turn exhibit a regular arrangement of elevations and depressions, are the etching patterns obtainable by etching surfaces." ..."The elevations / depressions may also have a fine structure, i.e., the elevations and depressions themselves have multiple elevations and / or depressions, wherein distances and height differences between adjacent elevations / depressions of the fine structure are at least a factor smaller than those of the associated main or superstructures. The average distances / height differences in the fine structures may, depending on the size of the superstructure, be in the range of 5 nm to 1000 nm, and in particular in the range of 10 nm to 500 nm."

[0013] A filling material as defined in this text can be in liquid, flowable, or solid form, although it is of course also possible for a liquid form to subsequently solidify and / or harden, or to harden independently (e.g., through contact with atmospheric moisture). Preferred filling materials are defined below, with water being excluded as a preferred filling material.

[0014] It is preferred that the filling compound to be provided according to the invention be solidifiable or solidified. It is particularly preferred that the apparent static contact angles described below are obtained in the solidified state. The apparent static contact angle, as defined in this text, is measured as described below in the measurement example.

[0015] For the purposes of this text, the angle formation “at or on” the boundary means that the corresponding angle can be observed either in the inner region of the boundary or on the boundary, since the boundary naturally must have a width. If the angle formation occurs on the boundary, this means, for the purposes of this text, that part of the micro- and / or nanostructure forming the boundary is not covered by the filler. This is preferred. In this case, an area surrounding the demarcated surface is always covered. However, it is also possible for the micro- and / or nanostructure forming the boundary to be completely covered by the filler. If the angle formation is present at the boundary, this means that the micro- and / or nanostructure forming the boundary is uncovered by the filler.

[0016] The delimitation of the defined area within the meaning of this text is achieved by means of microstructures and / or nanostructures such that the delimited area has a different structural configuration than the delimitation by the microstructures and / or nanostructures. It is preferred that the delimited area itself does not have any microstructures and nanostructures to be used according to the invention.

[0017] Furthermore, "demarcation" is generally understood to mean that a functional demarcation must be present, i.e., that the demarcation prevents the filler material from escaping from the demarcated area and forming a corresponding static contact angle. As can be seen from the attached Figure 1, this does not require a completely continuous demarcation, provided the interruptions in the structures forming the demarcation are small enough that the demarcated function is still fulfilled. For better understanding, reference is made to the corner areas of the demarcation in Figure 1.

[0018] Surprisingly, it has been found that the microstructures and / or nanostructures used according to the invention can effectively limit the spread of filler material onto a substrate. Surprisingly, even low-viscosity fillers can be used without exceeding the specified limits. Compared to the "Dam & Fill" technology described above, it also has the advantage that the material for the "dam" neither needs to be applied (time-consuming) nor disposed of after use. Furthermore, no additional materials remain on the substrate.

[0019] Furthermore, when inserting the filling material, there is no need to pay attention to interactions with the “dam material”, which significantly increases the flexibility with regard to the selection of filling materials.

[0020] In addition, the introduction of micro- and / or nanostructures, as described below, is possible with great spatial precision and, with suitable production processes, without significant energy load on the substrate. Accordingly, it is possible to create a corresponding propagation barrier for smaller structures. This is particularly true when the microstructuring or nanostructuring is created using laser processes. In particular, ultrafast laser technology is worth mentioning here, which can produce the microstructures or nanostructures used according to the invention within the framework of a cold ablation process without significant energy input into the substrate body (see also below).

[0021] According to the invention, it is preferred that, in preparation for applying the filler to the defined area, only the micro- and / or nanostructures are introduced around this area. In other words, it is preferred that the defined area itself remains unchanged. This results in the same surface conditions and surface properties preferably being present on both sides of the boundary formed by the micro- and / or nanostructuring. This has the advantage that, to achieve the desired result according to the invention, only the step of introducing the defining structures actually needs to be performed.

[0022] A further advantage of the solution according to the invention is that it is largely material-independent: a large number of materials and substrates, in particular circuit board materials and optoelectronic components, can be reproducibly structured.

[0023] The inventive approach can be used for a variety of technologies, such as encapsulation, bonding, or painting. In particular, applications requiring high precision at the micro-level, such as microelectronics and micro-optics, are easier to implement using the inventive solution. It is, of course, within the scope of the present invention that, depending on the requirements, there may be more than one area on a substrate defined by the microstructures used according to the invention.

[0024] In principle, it is also possible within the scope of the invention for the frame preferably provided according to the invention to be drawn around a component to be protected or the location for such a component. In this case, the defined area to which the filler compound is applied is the area outside this frame, although, of course, a further boundary must also be present here to prevent the uncontrolled spreading of the filler compound. In case of doubt, the edge of the substrate could also represent such a boundary. However, there are also cases in which the variant described here can be excluded from the invention.

[0025] According to the invention, a substrate according to the invention is preferred with at least one area delimited by means of microstructures and / or nanostructures and a filling material within the delimited areas, wherein the microstructures and / or the nanostructures cause an increase in the apparent static contact angle of the filling material compared to an identical surface without the structuring by > 5°, preferably > 10°, in each case more preferably > 15°, 20°, 25°, 30°, 40°, 45° and 50°.

[0026] In many cases, it may also be preferred according to the invention for the apparent static contact angle resulting at or on the boundary to be less than 89°, preferably less than 85°, more preferably less than 75°, more preferably less than 50°, and particularly preferably less than 45°. Surprisingly, it has been found that even such relatively small apparent contact angles are sufficient to effectively prevent spreading, which reduces the requirements for the respective limiting micro- and / or nanostructuring. For the measurement of the apparent static contact angle, reference is made to the corresponding measurement example below.

[0027] If the defined surface is uniform, i.e., one with a very low roughness value, it is clear to the person skilled in the art that the reference angle for the apparent static contact angle must be the static contact angle. The static contact angle is determined as explained in the measurement example for the apparent static contact angle.

[0028] The increase in the apparent static contact angle of the filler material reflects the fact that uncontrolled spreading through the microstructures and / or nanostructures is effectively prevented. It is self-evident that an overfilling of the defined area with filler material, despite the possible apparent static contact angle formation, would lead to an exceedance of the microstructures and / or nanostructuring to be provided according to the invention. Accordingly, the skilled person will avoid such an "overfilling" of the defined area.

[0029] According to the invention, a substrate according to the invention is preferred, wherein the microstructures and / or the nanostructures represent trenches running essentially parallel.

[0030] It is easily understood by the expert that the trenches should run parallel to the edge of the demarcated area.

[0031] This embodiment has proven particularly effective in inhibiting the spread of encapsulants, while also allowing the corresponding microstructures and / or nanostructures to be produced particularly easily, preferably using laser technology. It will be clear to a person skilled in the art that the parallelism of the trenches is meant to be parallel to the adjacent trench, so that in the case of, for example, a rectangularly defined area, parallelism is present within each side boundary, but not to microstructures and / or nanostructures that lie within an angled boundary line, such as a rectangular boundary line formed by the structuring to be used according to the invention.

[0032] It is therefore easy for the person skilled in the art to understand that the preferred design of the parallel trenches of the microstructures and / or nanostructures can of course apply to individual sides of the boundaries, but it is also preferably possible to produce curved, such as circular or elliptical boundaries.

[0033] A substrate according to the invention is preferred, wherein the microstructures and / or nanostructures form a closed frame or a frame that is (partially) open toward the edge of the substrate or another area that restricts the flow of the filler material. The frame is to be viewed as a functional frame intended, according to the invention, to inhibit the spreading. It is therefore easy to understand that interruptions in the frame that do not impair the function are considered frames within the meaning of this invention.

[0034] It is understandable to those skilled in the art that the edge of a substrate can also exert a flow limitation, provided that the defined area is not overfilled with the filler material. An "other flow-limiting region for the filler material" within the meaning of this text is an area on the substrate that represents neither a micro- and / or nanostructure used according to the invention nor an edge. Such areas can, for example, be elevations on the substrate, such as those provided, for example, by existing components. They can also be areas with a changed surface energy for reasons other than the structuring used according to the invention.In the context of the present invention, it should be noted that both the edge and the other flow-limiting areas for the filling compound, in combination with the respective filling compound, must allow filling of the defined area so that the above-mentioned apparent static edge angles can be formed.

[0035] This method allows for the creation of particularly well-defined areas to which the existing filler material is confined. With appropriate design, it is of course also possible to use the edges of the substrate as flow barriers for the filler material when applying the appropriate amount.

[0036] According to the invention, a substrate according to the invention is preferred with at least one area delimited by means of microstructures and / or nanostructures and a filling compound within the delimited area, wherein the length of the portion of the boundary formed by the microstructures and / or nanostructures immediately adjacent to the delimited area, based on the total circumference of the area, is > 30%, preferably > 40%, more preferably > 50% and in each case more preferably > 60%, > 70% and > 80%.

[0037] Within the scope of the present invention, it is therefore possible for the visible frame, which is preferred according to the invention, to also delimit a corner of the substrate and only contribute partially to the limitation of the spread of the filling compound, since the rest of the spread prevention is ensured by the lateral edge of the substrate or, for example, elevations on the substrate. In this case, as already mentioned above, attention should again be drawn to the problem of possible overfilling of the delimited area, which a person skilled in the art will avoid.

[0038] A substrate according to the invention is preferred, wherein the frame has a width of > 50 μm, preferably 100 μm - 5000 μm, and preferably 200 μm - 2000 μm. In the context of the present text, the frame width is understood to be the average width of the frame; in the case of an open frame towards the edge of the substrate, the edge region is of course not included.

[0039] In structuring, the preferred frame width described has proven to be quick and reproducible to produce, but in particular it has proven to be particularly effective for limiting the flow of filling materials.

[0040] The microstructures to be used according to the invention can preferably also be hierarchically (i.e., superimposed) with nanostructures. However, in some applications, it is preferred that only microstructures or only nanostructures be used on the substrate according to the invention for the delimitation.

[0041] A substrate according to the invention is preferred with at least one area defined by microstructures and a filling compound within the defined area, wherein the microstructures comprise or consist of trenches, with

[0042] - a depth of > 1 pm, preferably 1 - 100 pm and particularly preferably 10 - 20 pm and / or

[0043] - a width of 1 - 50 pm, preferably 5 - 20 pm and particularly preferably 10 - 15 pm and / or

[0044] - a distance from each other of 5 - 70 pm, preferably 35 - 60 pm and particularly preferably 40 - 50 pm and / or

[0045] - an opening angle of 5 - 40°, preferably 7 - 30° and particularly preferably 10 - 20°.

[0046] In case of doubt, the respective sizes are determined as described in the measurement examples below.

[0047] According to the invention, a substrate according to the invention may also be preferred with at least one area delimited by means of nanostructures and a filling compound within the delimited area, wherein the nanostructures comprise or consist of trenches with - a depth of > 10 nm, preferably > 50 nm and particularly preferably 100 - 400 nm and / or

[0048] - a width of 10 - 500 nm, preferably 40 - 400 nm and particularly preferably 40 - 300 nm and / or

[0049] - a distance from each other of 10 - 1000 nm, preferably 20 - 600 nm and particularly preferably 20 - 300 nm.

[0050] Here too, the nanostructures to be used according to the invention are determined as described in the measurement examples below.

[0051] Alternatively, it may be preferred according to the invention for the nanostructures, particularly when used in combination with microstructures, to not (only) form trenches, but also represent other structures, preferably typical laser-induced periodic surface structures (LIPSS structures). These LIPSS structures can have a wave-like trench structure. Particularly in combination with microstructures, these trenches can be interrupted, have the shape of rectangles or ovals, and be arranged less periodically.

[0052] A substrate according to the invention is preferred with at least one area delimited by means of microstructures and / or nanostructures and a filling compound within the delimited area, comprising in the region of the delimitation also nanostructures, preferably nanostructures as defined above as preferred.

[0053] It has been found that the microstructures and nanostructures described as preferred can effectively limit the spreading behavior of filling materials.

[0054] According to the invention, a substrate according to the invention is preferred with at least one area defined by microstructures and / or nanostructures and a filling compound within the defined area, wherein the structuring is at least in one direction

[0055] - an average roughness depth Rz S 0.1 pm, preferably 1 - 20 pm, particularly preferably 5 - 15 pm and / or

[0056] - an average profile element height Rc S 0.1 pm, preferably 1 - 50 pm, particularly preferably 1 - 10 pm and / or - an average spacing of the profile elements Rsm > 0.5 pm, preferably 20 - 100 pm and particularly preferably 30 - 70 pm.

[0057] The roughness values ​​are measured as shown in the corresponding measurement example below.

[0058] The setting of appropriate roughness values ​​is particularly helpful in the context of the present invention in order to achieve effective spreading control or spreading prevention of the filling material.

[0059] According to the invention, a substrate according to the invention is preferred, wherein the substrate is selected from the group consisting of wood, metal, semiconductor, glass, ceramic and plastic, preferably plastic.

[0060] It has been found that the preferred substrates mentioned can be microstructured or nanostructured particularly effectively for the purpose of the invention.

[0061] In general, it is preferred that the solution according to the invention can be used to locally limit coatings. Particularly preferred applications of these coatings are painting and bonding, as well as the use of casting compounds.

[0062] According to the invention, a substrate according to the invention is preferred, wherein the substrate is a circuit board, an electronic component, in particular a chip, or a (micro)optical element, in particular a lens. It is preferred that the substrate according to the invention comprises sensors, LEDs, chips, lenses, transistors, and / or batteries.

[0063] As already indicated above, the solution according to the invention is applicable to a wide variety of processes. Accordingly, a wide variety of filling materials can also be used according to the invention.

[0064] Accordingly, a substrate according to the invention is preferred, wherein the filler compound is selected from the group consisting of adhesive, potting compound, and paint, each preferably based on epoxy resins, acrylates, MS polymers, polyurethanes, polyimides, polyesters, or silicones. Optional solidification of the filler compound can occur due to physical and / or chemical processes, preferably due to chemical reactions, particularly preferably due to polymer formation reactions such as polyaddition, polycondensation, and polymerization.

[0065] It is preferred for the fillers to be used according to the invention to have a dynamic viscosity of <100,000 mPas, preferably <10,000 mPas, and particularly preferably <1,000 mPas upon application. Flow control is particularly important in these viscosity ranges; it goes without saying that the corresponding fillers can also be cured later. The viscosity is determined as indicated in the corresponding measurement example below.

[0066] Further preferred is a substrate according to the invention, wherein the microstructures and / or the nanostructures were produced by means of lithography, etching, embossing or laser, wherein production is carried out by means of lasers, particularly preferably by means of USP lasers with pulse lengths in the femtosecond (fs) to picosecond (ps) range.

[0067] There are numerous ways to produce the microstructures and / or nanostructures used according to the invention, making them technologically accessible for a wide variety of production lines. Laser technology, especially ultrafast laser technology, has proven to be particularly effective, precise, and easy to use.

[0068] Part of the invention is also the use of microstructures and / or nanostructures as defined above to limit the flow of a filling material.

[0069] In this case, the filling materials described above as being preferred are particularly to be mentioned, and it is preferred that the use according to the invention takes place in the form of a surface delimited by microstructures and / or nanostructures, in particular in the form of a frame or a frame open towards the edge.

[0070] The filling compound can be applied to the surface of the object in a conventional manner, in particular by brushing, coating, dipping (dip coating), spraying, spin coating, rolling, doctoring, or by means of a nozzle and dispenser, preferably by application using a nozzle and dispenser. Within the scope of the inventive use, it is thus possible to replace the wall of the above-described Dam & Fill process with the micro- and / or nanostructuring used according to the invention. The micro- and / or nanostructuring is preferably used in the form of a closed frame, but open frames, as described above, are also conceivable.

[0071] Part of the invention is also a method for producing a substrate according to the invention, comprising the steps of a) providing a substrate, b) providing a filling compound, c) microstructuring the substrate so that microstructures and / or nanostructures as defined above are produced and d) dosing filling compound onto the area delimited by the microstructures and / or nanostructures.

[0072] Step c) is of course carried out in such a way that the area delimited by the microstructures and / or nanostructures described above is created, whereby the delimitation is preferably in the form of a frame (see above).

[0073] It goes without saying that step d) is carried out by the person skilled in the art in such a way that the apparent static contact angle described above is created.

[0074] By means of this method according to the invention, the substrate according to the invention can be produced and the advantages of the solution according to the invention, as described in particular above, can be achieved.

[0075] In some cases, it may be preferred according to the invention for part or all of the substrate surface to be subjected to a pretreatment to improve wetting for the filler provided in step b). In particular, in such a case, the (later) delimited area will of course be treated accordingly. Preferred treatment methods are chemical and / or physical processes, in particular plasma treatment, laser treatment, or flame treatment. However, this does not constitute micro- or nanostructuring within the meaning of the invention. This optional pretreatment makes it possible to optimally prepare the substrate surface for the filler to be used.

[0076] In this sense, it may be preferable according to the invention to provide a solder resist coating on at least part of the surface of the substrate to be coated. Subsequently, microstructuring preferably takes place within the coated area, preferably such that the corresponding coating, in particular the solder resist, is still present on both sides of the boundary formed by the microstructuring.

[0077] A method according to the invention is preferred, wherein step c) is carried out by means of a laser, preferably with pulse lengths in the range 200 fs - 500 ns, particularly preferably USP lasers with pulse lengths of 200 fs - 500 ps and / or which emits in the near IR or in the IR range or which preferably emits in the range < 250 nm, more preferably < 200 nm.

[0078] The use of lasers, and in particular the use of ultrafast lasers, has proven particularly effective for producing the micro- and / or nanostructures used in the invention. These lasers allow a wide range of materials—including printed circuit board materials and reinforced plastics—to be reproducibly processed and structured at the micrometer to nanometer scale.

[0079] By selecting suitable laser parameters, in addition to cleaning and activating surfaces (i.e., increasing the surface energy, usually by introducing polar groups), a water-, adhesive-, or potting compound-repellent structure can be created, which is applied as a frame around the area to be contained. This allows for the control and limitation of the adhesive or potting compound flow and even increased fillability of the area to be contained.

[0080] In particular, using ultrashort pulsed lasers, even transparent plastics can be processed locally and with minimal damage by “cold ablation”, so that the structuring used according to the invention can be created without damaging the material.

[0081] In addition, the laser offers particularly good possibilities for forming very small structures. Especially when using ultrafast laser technology, it is also possible to work in close proximity to temperature-sensitive components, thus creating boundary frames around these components. Furthermore, the preferred ultrafast lasers are widely used in the electrical industry, where they are used for micromachining (e.g., cutting and drilling). Therefore, it is easily and economically feasible to apply these lasers to the inventive solution.

[0082] In the sense of the above-described, it is preferred according to the invention that the microstructures and / or nanostructures to be provided according to the invention, which form the boundary for the defined area, were produced by cold ablation.

[0083] A cold ablation within the meaning of the present text occurs when, according to measurement example 6 (see below), the FT-IR spectra of the micro- and / or nanostructured area and the non-nano- and / or microstructured area coincide for the person skilled in the art.

[0084] The "cold ablation" by means of a USP laser, which is preferably used according to the invention, leads primarily to a change in the topography, in contrast to thermal and / or chemical modifications for wetting control (e.g., by coatings with low surface energy or polarity or thermal processing). At least the chemical changes that can be caused by temperature are limited to the smallest areas. Thus, according to the invention, the "thermal influence zone" is preferably located below the maximum structure size generated, which cannot be resolved using established microscopic analysis techniques for detecting chemical changes on surfaces (see Measurement Example 6). According to the invention, wetting control in the demarcation area is therefore preferably carried out primarily by physical effects such as the adhesion of liquids to topographical heterogeneities (so-called pinning) and / or incomplete wetting due to the inclusion of gases (so-calledCassie condition) [Quere, David (2008): Wetting and Roughness. In: Annu. Rev. Mater. Res. 38 (1), pp. 71-99. DOI: 10.1 146 / annurev.matsci.38.060407.132434.].

[0085] It is clear to the person skilled in the art that, in the sense of the solution according to the invention, the filling compound is preferably applied in liquid or flowable form and is subsequently solidified in accordance with its actual purpose.

[0086] Accordingly, a method according to the invention is preferred in which solidification or curing of the filling compound occurs as step e). This allows the effect of the solution according to the invention to be achieved particularly advantageously, namely that local applications of filling compounds are possible without unwanted spreading, even in the smallest of spaces.

[0087] The application process, particularly the dosing speed, whether dosing is progressive or the filler material is withdrawn, influences the measured apparent static contact angle. Thus, the minimum contact angle according to the invention is the receding, apparent static contact angle, and the maximum measurable contact angle according to the invention is the advancing, apparent static contact angle.

[0088] Examples:

[0089] Measurement example 1: Determination of the apparent static contact angle

[0090] The term "apparent contact angle" takes into account that the contact angle at the transition point between the wetting surface and the less wetting frame lies at a three-phase point. Since the surface exhibits different topographies / roughnesses and chemistries across this point, the contact angle cannot be determined on a topographically and / or chemically homogeneous surface. To be able to describe this phenomenon, the apparent contact angle is considered macroscopic, i.e., the structuring is not taken into account, and the evaluation at the three-phase point (solid-liquid-gas) is based on a baseline projected across the surface. The determination of the apparent static contact angle is based on the standards DIN EN 828 and DIN EN 923 – albeit with some modifications (described with reference to Figure 2):

[0091] Figure 2 schematically shows the measurement conditions of the apparent static contact angle.

[0092] I limiting structuring

[0093] II Substrate surface without micro- and / or nanostructuring to be used according to the invention

[0094] III Filling mass IV Apparent static contact angle

[0095] 1 . The liquid filling compound is used as the test liquid.

[0096] 2. The filling compound is dosed at a maximum dosing rate of 40 pL / min exclusively into the area defined by the frame (II).

[0097] 3. The metered volume is increased as long as the frame (I) can fulfil its function according to the invention (i.e. overflow over the frame is avoided).

[0098] 4. The filling compound is optimally solidified immediately afterwards and according to the specifications, without moving the substrate or changing the ambient conditions (III).

[0099] 5. The substrate surface adjacent to the bordering structure forms the baseline in the projection (silhouette). The optionally solidified filler forms the droplet contour in the projection. Only the three-phase point located within the frame is evaluated.

[0100] 6. The contact angle (KW) thus determined is evaluated and averaged at at least 5 points of the delimiting structure.

[0101] Determination of the (apparent) static contact angle as a comparison value on substrates without a boundary: If no boundary structuring has been carried out, in step 2 the filler material is dosed onto a characteristic point on the substrate without the inventive structuring and at a sufficient distance from the edge and elevations, also at a maximum of 40 pL / min. To ensure comparability with the apparent static contact angle on a defined area (as described above), the same volume of filler material is dosed as on the substrate with a defined area. The apparent static contact angle in the three-phase point (i.e., at the edges of the liquid flow front) is then measured, evaluated, and averaged at at least five points as described above, only without a frame, after optional solidification, in accordance with the filler material specification, according to DIN EN 828.If the substrate surface is sufficiently smooth, the static contact angle fraction is evaluated instead of the apparent static contact angle.

[0102] Measurement example 2: Size determination of microstructures and nanostructures

[0103] The measurements were performed using a 3D microscope (type VHX-7000, manufacturer: Keyence). The images were taken at 1000x magnification. To determine the structure depths, structure widths, distances, and aperture angles, line profiles were created from the 3D images and characterized using the system's own evaluation software.

[0104] To determine the structure depth, a baseline was created at the tip and one in the middle of the depression area of ​​the microstructures. The depth is determined from the distance between these baselines, using the average of three individual measurements.

[0105] The structure width was measured at the beginning of the structures to the left and right of the plateau. The mean value of three individual measurements was reported.

[0106] Similarly, the distance between the structures was measured using the measurement distance at the beginning of the flanks to the right of the plateau. The mean value of three individual measurements was given in each case.

[0107] The opening angle is measured by creating two baselines on the two flanks of a structure and measuring the intersection angle using the software. The average value of three individual measurements was given in each case.

[0108] In this case, the nanostructures were characterized using a Phenom XL scanning electron microscope (Thermo Fisher) at an accelerating voltage of 10 kV (image mode). The width and spacing of the structures were determined using the system's own evaluation software at a magnification of 300. The depth and aperture angle were characterized using a VK9700 CLS ("confocal laser scanning") microscope (manufacturer: Keyence) based on height profile measurements perpendicular to the trench direction using the system's own evaluation software. Measurement Example 3: Determination of the Roughness of the Microstructures

[0109] To determine the roughness of the microstructured frame, line measurements are performed at representative locations on the frame using a laser scanning microscope (type: VK-X3100, manufacturer: Keyence) and a 20x objective lens perpendicular to the generated structures (e.g., grooves). For this purpose, five individual measurement sections with a reference length of 250 pm are defined across the frame width. Cutoffs are defined for evaluation with the device software (A s = 2.5 pm and A c = 250 pm) and the mean roughness depth R defined in DIN EN ISO 21920-2 z , average profile element height R c and mean distance of the profile elements Rsm evaluated.

[0110] Measurement example 4: Determination of the viscosity of the filling compound

[0111] The viscosity of the filler mass is determined in the ready-to-use state in a filler-dependent gap, in the case of the examples a 500 pm gap between two parallel aluminum plates (0 = 25 mm) in a DHR-2 rotational rheometer from TA Instruments. The shear rate, corrected by the system software, is continuously adjusted from 0.01 s -1 up to 100 s -1 increased while the shear stress is measured. The result is a curve showing the viscosity of the filler at the application temperature in the unsolidified state as a function of the shear rate. The dynamic viscosity is evaluated at a shear rate of 10 s -1 .

[0112] Measurement example 5: Proportion of the microstructured and / or nanostructured area compared to the substrate edge or elevation on the substrate

[0113] The corresponding determination is shown here using examples shown in Figure 3. In Figure 3, the following definitions apply:

[0114] I limiting micro- and / or nanostructuring

[0115] II demarcated area (without micro- and nanostructuring)

[0116] III Perimeter of the demarcated area or length of the microstructures and / or nanostructures of the demarcation immediately adjacent to the demarcated area

[0117] IV Substrate edge (analogously also elevation on the substrate). Figure 3a shows an area (II) completely delimited by microstructures and / or nanostructures (I). The extent of the micro- and / or nanostructuring directly adjacent to the delimited area is also marked (III) and amounts to 100% of the overall boundary. Part of the overall boundary can also be formed by the edge of the substrate or an elevation on the substrate (IV). Examples of such variants can be found in Fig. 3b), c), d), e) and f), with a proportion of micro- and / or nanostructuring of 50% (b.)), 41.5% (c.)), 75.5% (d.)), 100% (e.)) and 100% (f.)) of the overall boundary.

[0118] Measurement example 6: Detection of “cold ablation”

[0119] The evidence of “cold ablation” can be obtained, in addition to theoretical considerations on the physics of “cold ablation” at sufficiently high fluences (J / cm 2) and sufficiently short interaction durations (s) (e.g. Joglekar, Ajit P.; Liu, Hsiao-Hua; Meyhöfer, Edgar; Mourou, Gerard; Hunt, Alan J. (2004): Optics at critical intensity: applications to nanomorphing. In: Proceedings of the National Academy of Sciences of the United States of America 101 (16), pp. 5856-5861 . DOI: 10.1073 / pnas.0307470101 .; Bäuerle, Dieter (2011): Laser Processing and Chemistry. 4. 4th ed. 2011. Berlin, Heidelberg: Springer Berlin Heidelberg.; Prakash, S.; Kumar, S. (2017): Microchannel fabrication via direct laser writing. pp. 163-187.) experimental by comparative Fourier transform infrared spectroscopy (FT-IR).

[0120] For this purpose, point measurements are carried out using attenuated total reflection (ATR) with a microscopic FT-IR measuring device (LUMOS spectrometer from Bruker). For this purpose, at least one measuring point is placed centrally on the generated frame and at least one measuring point on the non-structured surface according to the invention. With medium contact pressure of the germanium crystal (standard crystal with a measuring tip diameter of 100 pm), an aperture of approximately 6.5 pm is set and a measurement is carried out with at least 128 scans per measuring point. The FT-IR spectra on the frame and the non-structured surface according to the invention are compared. If multiple measuring points are used per surface state, an average spectrum is calculated from the determined spectra and used for further comparison.

[0121] If the FT-IR spectra exhibit identical bands with identical intensities, meaning that the spectra can be considered congruent by a person skilled in the art, the thermal change is below the measurement resolution of the specified method. In this case, it is a "cold process" according to the invention, since, in particular, the structured areas do not differ (chemically) from the non-structured areas, or the changes are below the detection limit of the described measurement method.

[0122] Note: It must be verified whether the differences in band intensity between the frame and the unstructured surface are caused by the different contact area of ​​the ATR crystal surface, especially if the structure created by the laser is only of a small thickness. This does not constitute evidence of a thermal process.

[0123] • If the fluence during laser structuring is not sufficient for “cold ablation” according to theoretical descriptions (see above) or if changes occur between the FT-IR spectra of the treated and untreated surface, which can be caused by a thermal change and which can be recognized by the person skilled in the art (especially by the addition or omission of individual bands or changes in their intensities) using the method described, this is not a “cold process” according to the invention.

[0124] Example 1: Printed circuit board with potting compound

[0125] For the ultrashort pulsed laser treatment, the sample (type: Pump Control Board Assy PH602336 REV-7 (KK18020446), manufacturer: PerSeptive Biosystems) was positioned on a sample stage. The sample surface was then processed using a pulsed 10-watt ytterbium femtosecond fiber laser (type: YLPF-10-500-10-R, manufacturer: IPG Photonics), a 2D scan head (type: Rhino, manufacturer: Novanta Deutschland (formerly Arges)), and an associated telecentric f-theta lens (f=1632 mm) (type: S4LFT3163 / 126, manufacturer: SILL Optics). The emitted laser radiation has a central wavelength of 1030 nm, a laser pulse duration of approximately 500 fs, and a pulse repetition frequency of 500 kHz. The laser spot used had a beam diameter of 25 pm and a Gaussian energy distribution.

[0126] For the treatment of the surface, 100% of the maximum power of the system was used, which corresponds to a fluence of 4.7 J / cm 2on the sample surface. For the pretreatment of the substrates, a frame with various side lengths (5 mm - 30 mm) was exposed, and the surface was pretreated in the feed direction with 80% pulse overlap and a line spacing of 46 pm. The frame width can be selected from 200 pm - 2 mm (or more). The laser parameters selected in this way create trench-shaped microstructures on the GRP circuit board with solder mask, with trenches approximately 4-5 pm deep and 45 pm spacing (Fig. 1).

[0127] Data of the generated microstructures:

[0128] Depth: 4 - 5 pm

[0129] Width: 10 - 15pm

[0130] Opening angle: 10 - 20°

[0131] Distance: 40-50 pm

[0132] Geometry: parallel trenches or mountain-valley structures

[0133] The following roughness values ​​are also obtained for the generated frame structure: mean roughness depth R z= 12 pm

[0134] • average profile element height R c = 10 pm

[0135] • average distance between profile elements Rsm = 46 pm

[0136] The measurement according to Example 6 showed that the microstructuring was carried out as part of a cold ablation within the meaning of this application. r with the parameters from the 306 / 20+ Wevonat 300:

[0137] The potting compound Weropur 306 / 20+ Wevonat 300 (WEVO-Chemie GmbH) is applied with a syringe using the mixing ratio described in the data sheet onto a populated GRP circuit board with solder mask (type: Pump Control Board Assy PH602336 REV-7 (KK18020446), manufacturer: PerSeptive Biosystems). The volume of the potting compound is approximately 10 pL. If the potting compound is applied to an unconstrained substrate surface, the potting compound flows uncontrollably until an (apparent) static contact angle according to DIN EN 828 of < 14° is formed at the edges of the flow front. If the potting compound is applied into a field with a frame according to the invention, the potting compound flows until the field is completely filled; the frame structure is not exceeded. An apparent contact angle of > 50° is formed.

[0138] To demonstrate that the procedure is also suitable for encapsulating electronic components, a potting test was carried out using the same procedure.

[0139] For these tests, no "overfilling" was carried out, ie the indication that the apparent contact angle can also be greater than 50° is intended to show that the "possible apparent contact angle" can be even higher and consequently, with the technology, even higher components can be encapsulated, ie can be completely enclosed.

[0140] Example 3: Checking the wetting behavior and limiting the casting compound flow when using the casting compound ISOFILL BRW:

[0141] The ISOFILL BRW casting compound (ISO-ELEKTRA Elektrochemische Fabrik GmbH) is mixed according to the mixing ratio specified in the data sheet and proceeded analogously to the previous instructions. The apparent static contact angle is > 46° at the microstructure.

[0142] On the adjacent surface not structured according to the invention, the measured static contact angle is 23°.

[0143] As a further example, it was also shown that circular borders are also possible and that an inner frame is not wetted.

[0144] Example 4: Control of wetting or casting compound flow on other substrates:

[0145] It was also demonstrated that the structuring developed on conductor tracks can limit the adhesive flow on thermoplastics. This was demonstrated using polypropylene (supplier: Rocholl GmbH) as an example, with the same structuring as in Example 1. Example 5: Production of a microstructure in combination with a nanostructure on a titanium surface

[0146] For the ultrafast laser treatment, the sample (Ti6AI4V, supplier: ARA T Advance GmbH) was positioned on a sample stage. The sample surface was then processed using a pulsed 10-watt ytterbium femtosecond fiber laser (type YLPF-10-500-10-R, manufacturer: IPG Photonics), a 2D scan head (type: Rhino, manufacturer: Novanta Deutschland (formerly Arges)), and an associated telecentric f-theta lens (f=163 mm) (type: S4LFT3162 / 328, manufacturer: SILL Optics). The emitted, linearly polarized laser radiation has a central wavelength of 1030 nm and a laser pulse duration of approximately 270 fs. The laser spot used had a beam diameter of 30 pm and a Gaussian energy distribution.

[0147] In a first process step, a pulse repetition frequency of 150 kHz and a single pulse fluence of 1.4 J / cm 2A macrostructure is created. For the pretreatment of the substrates, a frame with various side lengths (5 mm - 30 mm) was exposed, and the surface was pretreated in the feed direction with 99.1% pulse overlap and a line spacing of 60 pm. The frame width can be selected from 200 pm - 2 mm (or more). The laser parameters selected in this way create parallel-aligned trenches on the titanium surface with the following dimensions:

[0148] Depth: 6 - 8 pm

[0149] Width: 30 - 40 pm

[0150] Opening angle: 15 - 20

[0151] Distance: 60 pm

[0152] Geometry: parallel trenches or mountain-valley structures

[0153] In this case, the structures were characterized using a Phenom XL scanning electron microscope (Thermo Fisher) at an accelerating voltage of 10 kV (image mode). The width and spacing of the structures were determined using the system's own evaluation software at a magnification of 300. The depth and aperture angle were characterized using a VK9700 CLS ("confocal laser scanning") microscope (manufacturer: Keyence) based on height profile measurements perpendicular to the trench direction using the system's own evaluation software. To create the nanostructures, the previously produced frame with the macrostructure was exposed a second time with the same laser system. For this second treatment, a frequency of 500 kHz and a single pulse fluence of 0.6 J / cm 2The pulse overlap in the feed direction was 93.3% at a line spacing of 2 pm. The laser parameters selected in this way create wave-like peak and valley structures (LIPSS structures) on the macrostructure with the following dimensions:

[0154] Depth: 300 nm

[0155] Width: 300 - 500 nm

[0156] Distance: 150 - 350 nm

[0157] Geometry: LIPSS (wave-like mountain and valley structures)

[0158] In this case, the structures were characterized using a Phenom XL scanning electron microscope (manufacturer: Thermo Fisher) at an accelerating voltage of 10 kV (image mode). The width and spacing of the structures were determined using the system's own evaluation software at a magnification of 6500. The depth and aperture angle were characterized using a VK9700 CLS ("confocal laser scanning") microscope (manufacturer: Keyence) based on height profile measurements perpendicular to the trench direction using the system's own evaluation software.

[0159] When measuring the contact angle analogously to Example 2, an apparent static contact angle of > 39° is formed on the titanium substrate in the area of ​​the structured frame.

Claims

Claims: 1 . Substrate with at least one surface delimited by means of microstructures and / or nanostructures and a filling material within the delimited surface, wherein the filling material forms an apparent static contact angle of > 20°, preferably > 30°, more preferably > 35°, even more preferably > 40° and particularly preferably > 42° at or on the boundary.

2. Substrate with at least one area delimited by means of microstructures and / or nanostructures and a filling material within the delimited area according to claim 1, wherein the microstructures and / or the nanostructures cause an increase in the apparent static contact angle of the filling material compared to an identical surface without the structuring by > 5°, preferably > 10°.

3. Substrate with at least one area defined by microstructures and / or nanostructures and a filling compound within the defined area according to claim 1 or 2, wherein the microstructures and / or nanostructures represent substantially parallel trenches.

4. Substrate with at least one area defined by microstructures and / or nanostructures and a filling compound within the defined area according to one of the preceding claims, wherein the microstructures and / or nanostructures form a closed frame or a frame open towards the edge or another area of the substrate which limits the flow of the filling compound.

5. Substrate with at least one area delimited by means of microstructures and / or nanostructures and a filling compound within the delimited area according to one of the preceding claims, wherein the length of the portion of the boundary formed by microstructures and / or nanostructures immediately adjacent to the delimited area, based on the total circumference of the area, is > 30%, preferably > 40%, more preferably > 50%.

6. Substrate with at least one area delimited by means of microstructures and / or nanostructures and a filling compound within the delimited area according to claim 4 or 5, wherein the frame has a width of > 50 pm, preferably 100 - 5000 pm and more preferably 200 - 2000 pm.

7. Substrate with at least one area defined by microstructures and a filling compound within the defined area according to one of the preceding claims, wherein the microstructures comprise or consist of trenches, with - a depth of > 1 pm, preferably 1 - 100 pm and particularly preferably 10-20 pm and / or - a width of 1 - 50 pm, preferably 5 - 20 pm and particularly preferably 10 - 15 pm and / or - a distance from each other of 5 - 70 pm, preferably 35 - 60 pm and particularly preferably 40 - 50 pm and / or - an opening angle of 5 - 40°, preferably 7 - 30° and particularly preferably 10 - 20°.

8. Substrate with at least one area defined by nanostructures and a filling compound within the defined area according to one of the preceding claims, wherein the nanostructures comprise or consist of grooves with - a depth of > 10 nm, preferably > 50 nm and particularly preferably 100 - 400 nm and / or - a width of 10 - 500 nm, preferably 40 - 400 nm and particularly preferably 40 - 300 nm and / or - a distance from each other of 10 - 1000 nm, preferably 20 - 600 nm and particularly preferably 20 - 300 nm.

9. Substrate with at least one area delimited by microstructures and a filling compound within the delimited area according to one of claims 1 to 7, comprising in the region of the delimitation also nanostructures, preferably nanostructures as defined in claim 8.

10. Substrate with at least one area defined by microstructures and / or nanostructures and a filling compound within the defined area according to one of the preceding claims, wherein the structuring is in at least one direction - an average roughness depth Rz S 0.1 pm, preferably 1 - 20 pm, particularly preferably 5 - 15 pm and / or - an average profile element height Rc S 0.1 pm, preferably 1 - 50 pm, particularly preferably 1 - 10 pm and / or - has an average spacing of the profile elements Rsm > 0.5 pm, preferably 20 - 100 pm and particularly preferably 30 - 70 pm.

11. Substrate with at least one area delimited by means of microstructures and / or nanostructures and a filling compound within the delimited area according to one of the preceding claims, wherein the substrate is selected from the group consisting of wood, paper, metal, semiconductors, glass, ceramics and plastic, preferably plastic, and / or wherein the substrate is preferably a printed circuit board, an electronic component or an optical element, and / or wherein the filling compound is selected from the group consisting of adhesive, potting compound and varnish, in each case preferably based on epoxy resins, acrylates, polyurethanes, polyimides, polyesters, MS polymers or silicones.

12. Substrate with a surface defined by microstructures and / or nanostructures and a filling compound within the defined surface according to one of the preceding claims, wherein the microstructuring and / or nanostructures were produced by means of lithography, etching, embossing, injection molding on structured tools or laser, preferably by means of laser.

13. Use of microstructures and / or nanostructures as defined in any one of the preceding claims for limiting the flow of a filling material.

14. A method for producing a substrate with a surface defined by microstructures and / or nanostructures and a filling compound within the defined surface according to one of claims 1 to 12, comprising the steps: a) providing a substrate, b) providing a filling compound, c) microstructuring the substrate so that microstructures and / or nanostructures as defined in any one of claims 1-10 or 14 are produced, and d) dosing filling compound onto the area delimited by the microstructures and / or nanostructures.

15. The method according to claim 14, wherein step c) is carried out by means of a laser, preferably with pulse lengths in the range 200 fs - 500 ns, particularly preferably USP lasers with pulse lengths of 200 fs - 500 ps and / or which emits in the near IR or in the IR range or which preferably emits in the range < 250 nm, more preferably < 200 nm, and / or wherein as step e) a solidification or curing of the filling compound takes place.

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