Radar sensor with waveguide structure

Abstract

To provide a radar sensor that can be manufactured with high cost effectiveness.SOLUTION: A radar sensor includes at least one high frequency module 16, and at least one waveguide structure 10 in the form of a plastic body having a conductive surface layer 38, and further includes at least one further plastic body 12, 14 having electrically conductive surface layers 28, 40, 30, 32, and the plastic bodies are thermally bonded together at their conductive surface layers.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present invention relates to a radar sensor comprising at least one high-frequency module and at least one waveguide structure in the form of a plastic body provided with a conductive surface layer. 【0002】 In particular, the present invention is directed to radar sensors used in motor vehicles for detecting the traffic environment, for example, within the framework of a driver assistance system, a collision warning system or an autonomous driving system. Typically, these radar sensors operate in a frequency band at 77 GHz. 【Background Art】 【0003】 Many common radar sensors use antennas formed from microwave substrates, but the present invention is directed to radar sensors in which the antennas are formed by waveguide structures. An example of this type of radar sensor is described in German Patent Application Publication No. 10 2018 203 106. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 German Patent Application Publication No. 10 2018 203 106 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 The problem of the present invention is to provide a radar sensor of such a type that can be manufactured with a higher cost-effectiveness. 【Means for Solving the Problems】 【0006】 This problem is solved in that the radar sensor according to the present invention comprises at least one further plastic body having a conductive surface layer, and these plastic bodies are thermally joined to each other by the conductive surface layers of the plastic bodies. 【0007】 In the context of this application, "thermal bonding" refers to a process in which materials are temporarily melted by the action of heat, and parts are connected to each other surface by means of soldering or welding, for example. This suggests that the plastic body is made of a plastic material with sufficient heat resistance. 【0008】 In known waveguide structures made of plastic, the conductive layer is formed on the inner surface of the waveguide cavity by, for example, coating, vapor deposition, sputtering, or galvanic connection. In the radar sensor according to the present invention, the plastic body also has a conductive surface layer on at least one outer surface, so that it can be reliably connected to each other mechanically and simultaneously electrically by soldering or welding. The conductive surface layer required for this can be efficiently formed in the same process as the conductive surface layer is formed on the inner wall of the cavity. 【0009】 The waveguide structure may be a waveguide antenna or a part of a waveguide antenna. At least one further plastic body may be a further waveguide antenna or a waveguide distributor structure for microwave output, or a plastic body used for centering, protecting, and / or electronically connecting high-frequency modules. According to the present invention, all of these components can be connected to each other efficiently and cost-effectively. It is also advantageous that thermal bonding enables microwave sealing of the waveguide structure and achieves low high-frequency attenuation of the components involved. For example, the manufacture of components from plastic by injection molding, injection compression molding, or extrusion molding, or possibly by partial material removal, allows for a high degree of design freedom. 【0010】 Advantageous and advanced forms of the present invention are described in the dependent claims. 【0011】 The conductive layer may be a surface layer coated with metal. In another embodiment, the conductive surface layer is formed by a layer of plastic containing special fillers such as CuSn, Fe, Cu, or SnZn, which make the plastic conductive and at the same time solderable. 【0012】 A radar sensor may have three or more plastic bodies connected to each other in a single soldering or welding process. The same soldering or welding process can also be used to connect high-frequency modules, such as MMIC chips (monolithic microwave integrated circuits) or RF-CMOS chips, to the waveguide structure. 【0013】 The exemplary embodiments will be described in more detail below with reference to the drawings. [Brief explanation of the drawing] 【0014】 [Figure 1] This is a schematic cross-sectional view of the radar sensor according to the present invention. [Figure 2] This is an exploded perspective view of three plastic parts that make up a radar sensor, viewed from an oblique angle above. [Figure 3] Figure 2 is an exploded view of the plastic body as seen from a diagonal downward angle. [Modes for carrying out the invention] 【0015】 The radar sensor shown in Figure 1 has three stacked plastic bodies that are plate-shaped as a whole. These plastic bodies form, from top to bottom in Figure 1, a first waveguide structure 10, a second waveguide structure 12, and a centering body 14 for the high-frequency module 16. The high-frequency module 16, such as an MMIC chip, is electrically and mechanically connected to a circuit board 20 by an array of solder contacts 18, such as a so-called ball grid. The circuit board 20 controls the MMIC and supports electronic components (not shown in detail) for further analyzing the received signal that has been previously analyzed by the MMIC. 【0016】 The centering body 14, which surrounds the high-frequency module 16 like a frame, has vias 22 (not visible in Figure 1, see Figure 2), which allow the second waveguide structure 12 to also be electrically connected to the circuit board 20, and further allow signal transmission between the circuit board and contacts 24 formed on the upper side of the high-frequency module. For this purpose, special conductive tracks 26 are formed on the underside of the second waveguide structure 12. In the region outside these conductive tracks, the second waveguide structure 12 has a conductive surface layer 28 on its underside, which is soldered face-to-face to a conductive surface layer 30 on the upper side of the centering body 14. A further conductive surface layer 32 on the underside of the centering body 14 is soldered to the ground electrode (not shown in detail) of the circuit board 20. Surface layers 30 and 32 are electrically connected in any suitable way, for example, by surface layers on the edges of the centering body. 【0017】 The first waveguide structure 10 forms a first waveguide antenna comprising a plurality of parallel waveguides 34, each waveguide opening to the upper side of the waveguide structure through the region of a radiating aperture 36. The inner walls of the waveguides 34 and the radiating aperture 36 are formed by a conductive surface layer 38. This surface layer 38 is also formed on the underside of the waveguide structure 10, where it is soldered face-to-face with a further conductive surface layer 40 located on the upper side of the second waveguide structure 12. 【0018】 The second waveguide structure forms a waveguide 42 (Figure 2) for connecting to the first waveguide structure 10. Simultaneously, the second waveguide structure 12 forms a second waveguide antenna with a lateral radiating aperture 44. The walls of the waveguide 42 and the radiating aperture 44 also have conductive surface layers that electrically connect the surface layers 40,28 on the upper and lower sides of the second waveguide structure 12 to each other. In this way, all conductive surface layers of the three plastic bodies are electrically connected to each other and to the ground electrode of the circuit board 20. 【0019】 As shown in FIG. 2, the centering body 14 has a square opening 46 in the center, and this opening 46 precisely accommodates a semiconductor module 16 (not shown in FIG. 2), aligning the waveguide structures 10, 12 and the high-frequency module 16 accurately with each other. 【0020】 The vias 22 are arranged at the corners of the centering body 14 and are each surrounded by an annular non-conductive region 48, which separates the vias from the surface layer 28 at ground potential. 【0021】 In FIG. 3, the underside of the waveguide structures 10, 12 and the centering body 14 can be seen. The vias 22 communicate with conductor tracks 50 on the underside of the centering body 14, and the conductor tracks 50 are coupled to corresponding signal electrodes and voltage supply electrodes of the circuit board 20 and are separated from the surface layer 30 by non-conductive regions 52. 【0022】 Under the second waveguide structure 12, obliquely extending conductor tracks 26 can be seen, and the conductor tracks 26 each connect one of the vias 22 to one of the contacts 24 of the high-frequency module 16. The conductor tracks 26 are also separated from the conductive surface layer 28 by non-conductive regions 54. 【0023】 Furthermore, the second waveguide structure 12 has waveguides 56, 58 on the underside, and the waveguides 56, 58 are each connected to the high-frequency module 16 via a high-frequency interface 60. The waveguides 56 each couple to one of the waveguides 42 for connecting the first waveguide structure 10, and the waveguides 58 each couple to one of the radiation openings 44 of the second waveguide antenna. 【0024】 Under the first waveguide structure 10, a waveguide 34 and the inner end of the radiation opening 36 can be seen. 【0025】 As shown in Figure 1, the waveguide structures 10, 12, the centering body 14, and the high-frequency module 16 are housed in a housing 62, the upper wall of which forms the radome of the radar sensor, the radome being at a predetermined distance from the radiation aperture 36 and made of transparent plastic to microwave radiation. 【0026】 When manufacturing the radar sensor described above, for example, the procedure may be to first cover the surface regions forming the non-conductive regions 48, 52, and 54 by any suitable method (e.g., pad printing, cover plate, cover foil), then form a conductive surface layer on the waveguide structure 12 and the centering body 14, and then remove the cover again. In another embodiment, the conductive surface layer may be formed continuously, and then the non-conductive regions may be formed by removing the conductive surface material in the non-conductive regions by laser ablation. 【0027】 A conductive surface layer 40 is provided on the first waveguide structure 10. Then, appropriate solder is applied to the surfaces to be soldered to each other, and the two waveguide structures 10, 12, the centering body 14, and the semiconductor module 16 are assembled integrally as shown in Figure 1, temporarily held together as a single unit, and soldered to each other in a single work process to form a unit. Then, in a further step, the unit thus obtained is soldered to the circuit board 20. 【0028】 Alternatively, the procedure could be to first place the high-frequency module 16 on the circuit board 20, then place the centering body 14, the second waveguide structure 12, and the first waveguide structure 10 in that order, align these components, and then solder all the components, including the circuit board 20, to each other in a single soldering process. 【0029】 In any case, the housing 62 is mounted separately in the final work step. Selectively, the radome, i.e., the upper wall of the housing 62, may be held at a predetermined distance from the radiating opening 36 by appropriate spacers, for example, by ribs on the upper side of the plastic body forming the first waveguide structure 10.

Claims

[Claim 1] It is a radar sensor, At least one high-frequency module (16) and The system comprises at least one waveguide structure (10) in the form of a plastic body having a conductive surface layer (38), The present invention comprises at least one further plastic body (12, 14) having a conductive surface layer (28, 40; 30), The aforementioned plastic bodies are thermally bonded to each other by the conductive surface layer of the plastic bodies. The at least one waveguide structure (10) is a waveguide antenna, The at least one further plastic body is a further waveguide structure (12), The further waveguide structure (12) forms a further waveguide antenna. A radar sensor characterized by the following features. [Claim 2] The radar sensor according to claim 1, wherein the plastic bodies are soldered to each other. [Claim 3] The radar sensor according to claim 1, wherein the conductive surface layers (28, 30, 38, 40) are made of heat-resistant conductive plastic. [Claim 4] The radar sensor according to claim 1, wherein the further waveguide structure (12) has a waveguide (42) for connecting the waveguide antenna to the high-frequency module (16). [Claim 5] The radar sensor according to claim 1, wherein at least one further plastic body, or one of the further plastic bodies, is a positioning body (14) for aligning the high-frequency module (16) with respect to the waveguide structure. [Claim 6] The radar sensor according to claim 5, wherein the positioning body (14) is coupled to the ground electrode of a circuit board (20) supporting the high-frequency module (16) via a conductive surface layer (32). [Claim 7] The radar sensor according to claim 6, wherein the positioning body (14) is a plate-shaped body having conductive surface layers (30, 32) electrically connected to each other on both sides. [Claim 8] The radar sensor according to claim 7, wherein the conductive surface layers (30, 38, 40) of all waveguide structures (10, 12) are connected to the ground electrode of the circuit board (20) via the positioning body (14). [Claim 9] The radar sensor according to any one of claims 6 to 8, wherein the positioning body (14) has vias (22) for connecting contacts of the circuit board (20) to conductor tracks (26) of the waveguide structure (12), and the conductor tracks (26) are coupled to contacts (24) of the high-frequency module (16).

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