A waveguide and method for the additive production of a waveguide

Abstract

A method for the additive manufacturing of a waveguide using a dielectric material for the fabrication of dielectric structures and a conductive material for the fabrication of electrically conductive structures is disclosed. The method comprises: additive manufacturing (S110) of at least one base body (110) using the dielectric material; forming (S120) a cavity (120); and additive manufacturing (S130) of a first conductor (131) and a second conductor (132) using the conductive material. The cavity (120) is formed at least partially between the first conductor (131) and the second conductor (132).

Description

[0001] The present invention relates to a method for the additive manufacturing of a waveguide and to a waveguide and in particular to the manufacturing of a microstrip structure or a coaxial structure for high-frequency signal guidance. BACKGROUND

[0002] There is a growing need to route high-frequency signals between components in the smallest possible space. As a result of increasing component integration, signals are not only required to be routed within a single plane, but also to be freely transmitted in space. This leads to the development of three-dimensional components designed to house numerous high-frequency technology components in a minimal footprint.

[0003] US 2018 / 0319108 A1 discloses an additive manufacturing process for electronic or mechanical structures, in particular a coaxial cable, on a substrate. Both conductive and non-conductive materials can be used in additive manufacturing.

[0004] Craton et al., "3D Printed High Frequency Coaxial Transmission Line Based Circuits", in: IEEE 67th Electronic Components and Technology Conference, 2017, disclose a method for manufacturing a coaxial structure using additive manufacturing technology. The coaxial structure consists primarily of dielectric material and is therefore relatively low-loss in the transmission of high-frequency signals (especially with frequencies above 10 GHz). A microstrip filter is also disclosed.

[0005] Sorocki et al., "Application of Additive Manufacturing Technologies for Realization of Multilayer Microstrip Directional Filter", in: IEEE 68th Electronic Components and Technology Conference, 2018, disclose a manufacturing process for a microstrip structure. In this process, an additively manufactured directional filter is assembled from two parts.

[0006] US 2017 / 062895 A1 discloses a waveguide that is additively manufactured by producing two component segments which are then joined together.

[0007] Conventional interconnections of various components are still based on printed circuit board structures to arrange components side by side, using, for example, coaxial cables for high-frequency signal transmission. However, these coaxial cables considerably limit the connection options. For instance, tight bends cannot be made, or can only be made to a limited extent, or are associated with a high loss factor.

[0008] Therefore, there is a need for waveguide structures that overcome the boundary conditions of conventionally manufactured waveguide structures. BRIEF DESCRIPTION OF THE INVENTION

[0009] At least some of the above-mentioned problems are solved by a method for the additive manufacturing of a waveguide according to claim 1 or a waveguide according to claim 10.

[0010] The dependent claims relate to further advantageous

[0011] Explanations of the subject matter of the independent claims.

[0012] The present invention relates to a method for the additive manufacturing of a waveguide using a dielectric material for the fabrication of dielectric structures and a conductive material for the fabrication of electrically conductive structures. The method comprises: Additive manufacturing of at least one base body using the dielectric material; forming a cavity; and additive manufacturing of a first conductor and a second conductor using the conductive material.

[0013] The cavity is formed, at least partially, between the first and second conductors. The first and second conductors can be additively manufactured and electrically insulated from each other.

[0014] It is understood that the sequence of process steps can be chosen arbitrarily or should only be restricted by the fact that one step is a prerequisite for a subsequent step. The term "additive manufacturing" is intended to specifically include a multi-material printer that can process at least one conductive and at least one non-conductive material. However, several materials can also be used (e.g., with different conductivities or dielectric properties) to produce, for example, passive components (e.g., electrical resistors, capacitors, etc.).

[0015] Optionally, cavity formation includes the following: providing a sacrificial structure; embedding the sacrificial structure by additively manufacturing the at least one base body; and partially or completely removing the sacrificial structure. Additive manufacturing of the first conductor and / or the second conductor may include additively manufacturing at least one conductive layer on a surface of the sacrificial structure. Removing the sacrificial structure may include pulling out, breaking out, and / or dissolving material from the sacrificial structure. Removal of the sacrificial structure may be complete or partial, meaning that remnants of the sacrificial structure may remain in the waveguide. Embedding may, in particular, include overprinting (in the sense of 3D printing).

[0016] Optionally, cavity formation includes the following: Forming a support structure within a portion of the cavity to prevent the ingress of dielectric or conductive material into the hollow body during additive manufacturing. After additive manufacturing, the waveguide may retain at least part of this support structure. The support structure can, for example, comprise a film (made of metal or plastic) that remains within the manufactured waveguide or later performs a function (e.g., shielding, insulation, etc.). The support structure can be positioned, in particular, in an upper region relative to the direction of additive manufacturing. This prevents additive manufacturing material from falling or dripping into the cavity.

[0017] Optionally, the additive manufacturing of the base body includes the following: additive manufacturing of a first component and / or a second component of the base body (e.g., separately); and joining the first and second components to form the base body. The hollow body may extend at least partially between the first and second components.

[0018] Optionally, the additive manufacturing of the base body and / or the first conductor and / or the second conductor includes the following: (continuous) layer-by-layer manufacturing in a single production plane, and curing of the dielectric and / or conductive material by contactless energy application. The cavity can be designed to be inclined relative to the production plane. Curing can occur between each application of one or more layers. Curing can involve, for example, irradiation with UV (ultraviolet) light, IR (infrared) light, a laser, or heat treatment, sintering, vaporization of a carrier fluid, production of ceramic materials, etc.

[0019] Optionally, the process also includes providing a component with a passive electrical component (e.g., a capacitor, a resistor, an inductor, etc.) and / or an active electrical component (e.g., with its own power supply connection). The additive manufacturing of the base body then includes at least a partial embedding of the component within the base body. Additive manufacturing can therefore take place around the component.

[0020] Optionally, the additive manufacturing of the base body includes the formation of openings to allow signals to be coupled out of the waveguide.

[0021] Optionally, the process includes evacuating and / or sealing the cavity, for example, to prevent air ingress. The cavity formed by additive manufacturing can be filled with any gas (e.g., air or an inert gas such as a noble gas) to conduct an electric field and minimize dielectric losses. The cavity can be evacuated after additive manufacturing, and sealing the cavity can maintain a vacuum to conduct the electric field and further minimize losses.

[0022] Optionally, additive manufacturing includes additive inkjet printing, in which a dielectric functional fluid (e.g., a dielectric ink) is selectively used as the dielectric material and a conductive functional fluid (e.g., a conductive ink) as the conductive material. Conductivity can be achieved through conductive particles in the fluid (e.g., silver nanoparticles).

[0023] Optionally, additive manufacturing can also include a sintering process (laser sintering), where, for example, powdered material is sintered using a laser.

[0024] Optionally, the first conductor and / or the second conductor can each be formed as a layer. This layer(s) can extend parallel to opposite sides of the hollow body (partially or completely), so that the waveguide forms a microstrip structure.

[0025] Other methods involve forming at least one additional conductor within the base body, with the additional conductor optionally being electrically insulated from both the first and second conductors. For insulation, the conductors can be separated, for example, by a portion of the dielectric base body. The first conductor can be formed at the bottom of the cavity. For instance, the first conductor can define the bottom boundary of the cavity. The second conductor and / or the additional conductor can be partially formed on an opposite boundary (opposite to the bottom) of the cavity, on the same plane. The bottom can, for example, be formed first using additive manufacturing; that is, the terms "top" and "bottom" can be defined by the additive manufacturing direction (the "growth" of the waveguide).

[0026] Forming the cavity creates a hollow cylinder. The first conductor can be configured as an inner conductor, and the second conductor as a shield that partially or completely surrounds the inner conductor. The waveguide thus forms a coaxial structure.

[0027] In a cross-sectional view, the inner conductor appears as a pyramid-shaped protrusion into the cavity. This pyramid-shaped protrusion can be made of conductive material or partially (e.g., in a radially outer region) of dielectric material.

[0028] Exemplary embodiments also relate to a waveguide, which in particular forms a microstrip structure or a coaxial structure. The waveguide comprises: a dielectric base body, a cavity, a first conductor, and a second conductor. The dielectric base body has a microstructure corresponding to an additive manufacturing process. The first conductor and the second conductor can have a microstructure corresponding to an additive manufacturing process and are in direct contact with the cavity to form the waveguide. The microstructure refers to a microscopic arrangement of the material that is typical for the additive manufacturing process used.

[0029] Examples of implementation should not be limited to waveguide applications. In fact, additive manufacturing can be used to create any functional structure. Likewise, any topology can be created. The additive manufacturing plane does not restrict the orientation of components. In particular, signal lines or waveguides can run non-parallel to the manufacturing plane. They can also be intertwined. In all three spatial directions, any topology can be created by arranging the components of a part.

[0030] Examples of implementation offer the following advantages: A frequency range above the physical cutoff frequency with a loss factor of 0.2 dB / cm for the non-conductive material used is possible. There are no geometric limitations, in particular no restrictions regarding the radii of waveguide structures. Unlike conventional coaxial cables, curves with any radii of curvature can be generated (e.g., less than or equal to the diameter of the waveguide). Due to additive manufacturing, there are no surface stresses at curves along the hollow waveguide, resulting in improved signal transmission. BRIEF DESCRIPTION OF THE FIGURES

[0031] The embodiments of the present invention are better understood from the following detailed description and the accompanying drawings, which, however, should not be understood as limiting the disclosure to the specific embodiments, but merely serve for explanation and understanding. Fig. 1 shows a schematic flowchart of an additive manufacturing process according to an embodiment of the present invention. Fig. 2 shows a cavity-guided microstrip structure according to an example that is not covered by the scope of the claims. Fig. 3 shows a cavity-guided coaxial structure according to an embodiment. DETAILED DESCRIPTION

[0032] Fig. 1 Figure 1 shows a schematic flowchart of an additive manufacturing process using a dielectric material to fabricate dielectric structures and a conductive material to fabricate electrically conductive structures. The process comprises the following steps: Additive manufacturing S110 of at least one base body using the dielectric material; forming S120 of a cavity; and additive manufacturing S130 of a first conductor and a second conductor using the conductive material.

[0033] According to the exemplary embodiments, an inkjet process can be used for additive manufacturing. However, according to further exemplary embodiments, laser sintering or another 3D printing process can also be used.

[0034] The laser sintering process can utilize, for example, a so-called "low-temperature cofired ceramic" (LTCC) process. This method is based on low-temperature cofired flexible ceramic films, whereby the unfired films can be mechanically structured and then printed, laminated, and sintered at approximately 850 to 900°C using thick-film technology. The result is a highly integrated, three-dimensionally cross-linked, multilayer ceramic board.

[0035] Further processing is carried out using established layer, bond, and SMD (surface-mount device) technologies. The substrate material is ceramic. Its dimensional stability in the unfired state enables a completely new connection and packaging system. In particular, recesses, chip carrier structures, windows, even complex external contours and three-dimensional shapes can be implemented in channels and chambers. The favorable electrical properties and the low resistance of the internal conductor tracks enable a high-frequency design with excellent performance. All components can be placed in the smallest possible space and optimally connected thanks to an unlimited number of layers.

[0036] In inkjet printing (so-called inkjet process), a conductive and a non-conductive functional fluid (e.g., ink) are used, according to exemplary embodiments. These fluids are additively applied to a substrate and processed into a three-dimensional structure. This process is used, for example, in so-called AME (Additive Manufactured Electronics). For instance, a photopolymer fluid can be used as the ink for non-conductive structures, and a silver nanoparticle fluid for conductive structures. The curing process can be carried out using ultraviolet light, according to exemplary embodiments. The result is a three-dimensional solid body that has been additively manufactured layer by layer in a single build direction.

[0037] According to further embodiments, a nanoparticle sintering process is used for curing, whereby sintering is possible at a fraction of the melting temperature of the conductive material.

[0038] AME manufacturing enables the combination of E-CAD (electrical computer aided design) and M-CAD (mechanical computer aided design) in three-dimensional space and is particularly suitable for the implementation of hybrid modular concepts.

[0039] Fig. 2 Figure 1 shows an example of a cavity-guided microstrip structure manufactured using additive manufacturing. The microstrip structure comprises a base body 110 in which a hollow body 120 is formed. The hollow body 120 is bounded on one side by a first conductor 131 (e.g., at a base). On the side of the cavity 120 opposite the first conductor 131, a second conductor 132 is formed. Furthermore, another conductor 133 is formed within the microstrip structure. The second conductor 132 and the other conductor 133 can, for example, be located on the same plane, whereby the plane can be defined with respect to the manufacturing plane.

[0040] The second conductor 132 and the further conductor 133 are electrically separated from each other by a dielectric insulating section 140, which can be part of the base body 110 or the cavity 120. For example, one or more of the conductors 131, 132, 133 can extend to a surface area of ​​the base body 110 (e.g., they can be electrically contacted there). It is also possible for the conductors 131, 132, 133 to be completely embedded in the dielectric base body 110 and to form current channels.

[0041] In the example of the Fig. 2 For example, the first conductor 131 is formed in a bottom area of ​​the cavity 120, but does not extend to the lateral edges of the base body 110. It can optionally represent a ground. In contrast, the second conductor 132 extends to a left edge of the base body 110 and can be electrically connected there. The same applies to the further conductor 133, which extends to a right lateral wall of the base body 110, for example, to be electrically connected there.

[0042] To allow for maximum design freedom with regard to the cavity 120, support structures or sacrificial structures are used according to exemplary embodiments. These structures can remain at least partially within the waveguide after additive manufacturing, or can be partially or completely removed. For example, sacrificial structures can be washed or broken out once the base body has cured. Alternatively, it is also possible for a support structure (for example, a film) to remain within the additively manufactured waveguide and simultaneously fulfill a specific function (e.g., signal guidance, shielding, insulation, etc.).

[0043] Fig. 3 Figure 1 shows an embodiment for a cavity-guided coaxial structure. In this embodiment, the waveguide is manufactured using two components, but it can also be printed monolithically, as in the embodiment shown in Figure 2. Fig. 2 , which, incidentally, does not have to be manufactured monolithically, but can be assembled from several components.

[0044] In component manufacturing, as exemplified in the Fig. 3 As shown, a lower, first component 111 can first be additively manufactured. The first component 111 includes a recess that forms part of the cavity 120 in its lower region. An upper, second component 112 of the base body 110 is also additively manufactured; this component also has a recess that will later become part of the cavity. The first and second components 111 and 112 are then joined, for example, by inserting the second component 112 into the recess of the first component 111. Subsequently, the two components 111 and 112 can be bonded or sealed. The additive manufacturing process can also be used for this purpose.

[0045] According to the exemplary embodiments, the second component 112 is manufactured using the same or a different additive manufacturing process. Optionally, the second component 112 can include openings 150, which can serve, for example, for coupling in or out a high-frequency signal or for inserting further components. The shape and number of openings 150 are shown only as examples. Fig. 3 will be shown. It is understood that the openings 150 can be adapted to the desired function with regard to shape, position and orientation.

[0046] To form a coaxial conductor, an inner conductor 131 is additively manufactured in the recess, with the inner conductor 131 projecting pyramidally into the cylindrical cavity 120 and extending along its channel-like exterior. The pyramidal projection need not be formed entirely of conductive material (but it can be). The inner conductor 131 only needs to be formed at one apex of the pyramidal projection. Furthermore, on an inner surface of the second component 112 and / or the first component 111 of the base body 110, the second conductor 132 is formed as a surface layer to provide shielding. Both the inner conductor 131 and the shield 132 are additively manufactured from conductive material, with the shield 132 extending completely around the outer wall of the hollow body 120, while the inner conductor 131, as already mentioned, only needs to be formed at the apex of the pyramid.

[0047] Further embodiments relate to a coaxial waveguide that is formed monolithically. Therefore, the two components 111, 112 do not need to be manufactured separately; rather, the cavity-guided coaxial structure can be produced as a single piece. To manufacture the cylindrical cavity 120, for example, a sacrificial or support structure can be introduced or formed within the cavity 120 to achieve the fabrication of the superstructure without the additive manufacturing material falling into the cavity 120.

[0048] The base body 110 again comprises an electrically non-conductive material, for example, a first dielectric. The cavity 120 can also be filled with a second non-conductive material (e.g., a second dielectric). The dielectrics can be selected such that an electromagnetic wave is guided along the waveguide as desired. As before, the cavity 120 can again be evacuated or filled with gas.

[0049] It goes without saying that additive manufacturing is a distinguishing feature of the manufactured product. In Depending on the additive manufacturing process used (whether laser sintering, inkjet printing, or another method), the microscopic structure differs. A person skilled in the art can determine which additive manufacturing process was used based on the microscopic structure. Another structural feature that can distinguish an additively manufactured component from a conventionally manufactured component (e.g., using casting or machining) is the presence of sacrificial structure remnants, which may be optionally present to create overhangs or covers.

[0050] Additive manufacturing not only represents an alternative production method, but also offers advantages that are unattainable with conventional manufacturing. These advantages include, in particular, the design freedom when arranging interconnects in any topology. Tight bends in various directions are not only possible, but also result in no mechanical stresses in the curved section of the waveguide.

[0051] In particular, the waveguide can run in any direction, even obliquely to the manufacturing plane, where the manufacturing plane is defined by the layers that are cured sequentially during additive manufacturing. The layer-by-layer curing process includes, in particular, the contactless application of energy, such as irradiation. Irradiation can be achieved using a laser or an ultraviolet or infrared light source. It is also possible to use heat treatment (e.g., heating) or a sintering process to cure the individual layers. Sintering is particularly suitable for producing ceramic materials. If the additive manufacturing process involves inkjet printing, curing can involve the evaporation of a carrier fluid.

[0052] As the exemplary embodiment of the Fig. 3 As demonstrated, this method enables the creation of waveguides of any shape. In particular, tight bends of 90° and more can be generated, along which a high-frequency signal can be guided. No bending of an existing waveguide (e.g., a coaxial cable) is required. This allows the waveguide to extend through the component not only parallel to a layer, but also at an angle greater than 1° or less than 90° to the layers, thus enabling three-dimensional signal transmission across multiple layers.

[0053] According to exemplary embodiments, any number of separate conductive elements (such as electrodes, contact leads) can be arranged. Thus, not only the waveguide can be formed in a three-dimensional substrate, but also any number of feed electrodes or other conduction elements can be accommodated, which are directly embedded in the base body 110 of the waveguide.

[0054] Likewise, at least one active or passive component can be embedded in the base body 110 or manufactured using additive manufacturing. This results in a compact design and a high level of protection against environmental influences. As already mentioned in the Fig. 3 As explained, the desired structures can be produced in one piece or in multiple pieces. In multi-piece production, individual components are manufactured separately and then assembled.

[0055] The advantages of exemplary implementations can be summarized as follows: The usable frequency range increases; furthermore, an increase in the degree of integration for high-frequency signal transmission becomes possible; an increase in 3D design degrees of freedom is achieved; the integration of parts and coupling structures becomes possible; any combination of high-frequency signal transmissions with antenna structures and active circuit elements is possible (for example, sensor elements, digital or transmit / receive circuits can be embedded); the possible implementation of a complex system in a single manufacturing step becomes possible.

[0056] The features of the invention disclosed in the description, claims and figures may be essential for the realization of the invention, either individually or in any combination. REFERENCE MARK LIST

[0057] 110 Base body 111, 112 Components of the base body 120 Cavity 131, 132, 133 Conductor 140 Insulation section 150 Opening(s) in the base body

Claims

1. Method for the additive manufacturing of a waveguide using a dielectric material for manufacturing dielectric structures and a conductive material for manufacturing electrically conductive structures, comprising the following steps: additive manufacturing (S110) of at least one main body (110) using the dielectric material; forming (S120) a cavity (120); and additive manufacturing (S130) of a first conductor (131) and a second conductor (132) using the conductive material, wherein the cavity (120) is formed at least in part between the first conductor (131) and the second conductor (132), and wherein the additive manufacturing of the main body (110) comprises the following: additive manufacturing of a first component (111) and a second component (112) of the main body (110); and joining the first component (111) and the second component (112) in order to form the main body (110), wherein the cavity (120) extends at least in part between the first component (111) and the second component (112), and wherein the forming (S120) of the cavity (120) produces a hollow cylinder and the additive manufacturing (S130) of the first conductor (131) produces an inner conductor and the additive manufacturing (S130) of the second conductor (132) produces shielding, which extends around the inner conductor, such that the waveguide forms a coaxial structure, wherein, when viewed in cross section, the inner conductor (131) is in the form of a pyramidal projection into the cavity (120).

2. Method according to claim 1, wherein the forming (S120) of the cavity (120) comprises the following: providing a sacrificial structure; embedding of the sacrificial structure by the additive manufacturing (S110) of the at least one main body (110); and removing the sacrificial structure, wherein the additive manufacturing (S130) of the first conductor (131) and / or the second conductor (132) comprises additive manufacturing of at least one conductive layer on a surface of the sacrificial structure, and wherein the removal of the sacrificial structure includes pulling out, breaking out, or dissolving a material of the sacrificial structure.

3. Method according to either of the preceding claims, wherein the forming (S120) of the cavity (120) comprises the following: forming a support structure in a region of the cavity (120) to prevent the ingress of dielectric material or conductive material into the cavity (120) during additive manufacturing, wherein, after the additive manufacturing, the waveguide comprises at least part of the support structure.

4. Method according to any of the preceding claims, wherein the additive manufacturing (S110) of the main body (110) and the additive manufacturing (S130) of the first conductor (131) and / or the second conductor (132) comprises the following: continuous layer-by-layer manufacturing in one manufacturing plane, and, between each application of a layer, curing the dielectric and / or conductive material by contactlessly introducing energy, wherein the cavity (120) is inclined with respect to the manufacturing plane.

5. Method according to any of the preceding claims, further comprising the following: providing a component with a passive electrical component and / or an active electrical component, wherein the additive manufacturing (S110) of the main body (110) includes at least partial embedding of the component in the main body (110).

6. Method according to any of the preceding claims, wherein the additive manufacturing (S110) of the main body (110) comprises forming openings in order to allow outcoupling of signals from the waveguide.

7. Method according to any of the preceding claims, further comprising the following: evacuating the cavity (120); and sealing the cavity (120) to prevent air from entering.

8. Method according to any of the preceding claims, wherein the additive manufacturing comprises additive inkjet printing, which selectively uses a dielectric functional fluid as the dielectric material and a conductive functional fluid as the conductive material.

9. Method according to any of the preceding claims, wherein the additive manufacturing (S130) of the first conductor (131) and the second conductor (132) in each case produce a layer, which layers extend in parallel on opposite sides of the cavity (120), such that the waveguide forms a microstrip structure.

10. Waveguide comprising: a dielectric main body (110), which has a microstructure corresponding to an additive manufacturing process; a cavity (120); and a first conductor (131) and a second conductor (132), which have a microstructure corresponding to an additive manufacturing process and which are in direct contact with the cavity (120) in order to form the waveguide, wherein the main body is formed by an additively manufactured first component (111) and an additively manufactured second component (112), wherein the cavity (120) extends at least in part between the first component (111) and the second component (112), and wherein the cavity (120) is a hollow cylinder, and the first conductor (131) forms an inner conductor, and the second conductor (132) forms shielding, which extends around the inner conductor, such that the waveguide forms a coaxial structure, wherein, when viewed in cross section, the inner conductor (131) is in the form of a pyramidal projection into the cavity (120).

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