Radar sensor with waveguide structure

Abstract

Radar sensor having a high-frequency component (14) arranged on a circuit board (10) and a waveguide structure (22; 22") connected to the high-frequency component (14) by a coupling structure (36), characterized in that the waveguide structure (22) is formed in a molded body (20) which is injected into a portion of the circuit board (10) carrying the high-frequency component (14).

Description

Technical Field

[0001] The present invention relates to a radar sensor having a high-frequency component arranged on a circuit board and a waveguide structure connected to the high-frequency component by a coupling structure. Background Technology

[0002] This type of radar sensor is described in DE 10 2014 208 389 A1, in which the waveguide structure is a waveguide antenna array. Summary of the Invention

[0003] The objective of this invention is to realize a radar sensor that can be easily manufactured with low manufacturing tolerances and is robust to environmental influences.

[0004] According to the present invention, this task is solved by forming a waveguide structure in a molded body, which is then sprayed onto a portion of a high-frequency component of a circuit board.

[0005] When the molded body is sprayed onto the circuit board, precise alignment of the circuit board with the tool used to form the molded body allows the waveguide structure to be positioned and molded relative to high-frequency components with tight dimensional tolerances. Simultaneously, the material-locking connection between the molded body and the circuit board eliminates the need for additional fastening mechanisms that could lead to subsequent product deformation. It also avoids the formation of easily corroded seams between the molded body and the circuit board.

[0006] Advantageous extensions and configurations of the invention are described in preferred embodiments.

[0007] In one embodiment, the high-frequency components, or possibly an arrangement of multiple high-frequency components, are arranged on the same side of the circuit board as the waveguide structure, and the one or more high-frequency components are also injection molded over a molded material. However, embodiments are also conceivable in which the high-frequency components and the waveguide structure are located on opposite sides of the circuit board and the coupling structure includes a feedthrough through the circuit board. It is also conceivable that the circuit board is injection molded over both sides of the circuit board. In this case, the waveguide structure can be located on both sides of the circuit board.

[0008] Waveguide structures can form waveguide antennas or waveguide antenna arrays and / or distributor networks that connect the antennas to high-frequency components in terms of signal technology. Optionally, waveguide structures can also have multi-layered waveguides. In this case, different layers can be fabricated in successive steps during injection molding.

[0009] The molded body can be formed from a non-conductive material such as thermoplastic or thermosetting plastic, in which only the walls of the waveguide have a conductive coating. In another embodiment, the molded body can be composed entirely of a conductive material, such as a plastic containing a certain amount of conductive particles, which makes the material conductive overall. Here, the material content and particle size of the conductive particles are chosen in such a way that sufficient conductivity is achieved even when the skin effect is taken into account.

[0010] In one embodiment, the waveguide structure has cavities open toward the outer surface of the molded body. These cavities are then closed by a cover, which has a conductive layer at least on the side facing the molded body. In the case of a waveguide antenna, the cover may have appropriately sized and molded openings for transmitting and receiving radar signals.

[0011] The cover may be made entirely of a metal sheet or of plastic that has been metallized on at least one side. In the latter case, the cover may be an additional molded body into which the radome is integrated and / or the additional molded body has reliefs for suppressing unwanted microwave reflections.

[0012] These features can also be advantageous regardless of the basic technical solution of the present invention. Therefore, a radar sensor is also disclosed having waveguide antennas, the waveguides of which are formed by cavities formed in a substrate and open toward the outer surface of the substrate. The radar sensor also has a cover that completely or partially seals the cavities with a conductive layer, wherein the cover is formed of a molded body in which an antenna radome is integrated and / or the outer surface of the molded body has an embossed design.

[0013] Alternatively or additionally, a heating device for the radome or at least one plug connector for connecting an external radome heating device may also be integrated into the molded body.

[0014] The outer surface of the molded body in which the waveguide structure is formed may also have an embossed design, thereby forming, for example, a multiplanar antenna array or a conformal antenna array (i.e., the radiating surfaces of the antenna elements are located in planes that are inclined to each other or are part of a curved surface). If the embossing on the outer surface does not have a lateral recess, the cover may be a one-piece molded body with a surface complementary to the embossing. Attached Figure Description

[0015] The embodiments are described in more detail below with reference to the accompanying drawings.

[0016] The attached diagram shows:

[0017] Figure 1 A schematic cross-sectional view of a radar sensor according to the present invention is shown;

[0018] Figures 2 to 4 Cross-sectional views of different variations of another embodiment of the present invention are shown;

[0019] Figures 5 to 7 A schematic cross-sectional view is shown of a high-frequency component that can be used in a radar sensor according to the present invention;

[0020] Figures 8 to 11 A cross-sectional view of a radar sensor according to another embodiment of the present invention is shown;

[0021] Figure 12 An exploded cross-sectional view of a radar sensor with a covered, enclosed waveguide structure is shown.

[0022] Figures 13 to 16 Cross-sectional views of different embodiments of the cover are shown;

[0023] Figure 17 and Figure 18 A cross-sectional view of a radar sensor according to another embodiment of the present invention is shown; and

[0024] Figure 19 An exploded perspective view of a radar sensor according to another embodiment of the present invention is shown. Detailed Implementation

[0025] exist Figure 1The radar sensor shown in the cross-sectional view has a circuit board 10, which has a high-frequency compatible carrier substrate 12 on its upper side and is equipped with a high-frequency component 14. The high-frequency component 14 may be, for example, an MMIC package (a monolithic microwave integrated circuit with a plastic housing). On the lower side, the circuit board 10 is equipped with other electronic components 16 (e.g., ICs, SMDs (Surface Mount Devices)) in a known manner and is equipped with a connection unit 18 for connecting a connector. The entire circuit board 10, including the components disposed thereon (except for a portion of the connection unit 18), is injection molded from a non-conductive plastic body 20, preferably from a thermosetting plastic, and optionally from a thermoplastic plastic. A waveguide structure 22 is formed in the upper side of the molded body 20, the waveguide structure having a plurality of cavities 26 opening toward the outer surface 24 of the molded body, the walls of which are made conductive by metallization 28. Cover 30 is mounted on outer surface 24 using any known joining technique, such as welding or bonding. This cover covers all cavities 26 and is electrically connected to the metallized portions 28 of these cavities, thereby enabling the cavities 26 to function as waveguides. In some regions of the cavities 26, cover 30 has openings 32 through which microwaves can be transmitted and / or received, thus enabling the associated cavities to function as waveguide antennas. The remaining waveguides of waveguide structure 22 form a distributor network through which radar signals generated in high-frequency components 14 are transmitted to the waveguide antenna and / or radar signals received by the waveguide antenna are transmitted to high-frequency components 44. To signal-technically couple high-frequency components 14 to waveguide structure 22, high-frequency lines 34, such as microstrip lines, are formed on carrier substrate 12, which are coupled to one of the waveguides via coupling structure 36. It is understood that radar sensors may have multiple high-frequency components 14 on the same circuit board 10, each coupled to the waveguide antenna via its respective distributor network.

[0026] In manufacturing the radar sensor, the circuit board 10 is first equipped with high-frequency components, other electronic components, and a switching unit 18. Then, the circuit board is injection molded into a molded body 20, with alignment marks (not shown) used to ensure precise alignment of the molding tool with respect to the circuit board. After demolding, the walls of the cavity 26 (except for the free end of the coupling structure 36) are metallized with metallized portions 28, and finally, the cavity is sealed with a cover 30.

[0027] In the example shown, the cover 30 is simply formed from a metal sheet. However, in other embodiments, the cover may also be a metallized plastic sheet or a metallized molded body made of plastic.

[0028] Figure 2A variant embodiment is shown in which the high-frequency component 14 is a bare chip MMIC disposed on a redistribution plane 38 and encapsulated in a package 40, which also forms part of a coupling structure 36. In this case, the high-frequency lines 34 for coupling to the coupling structure 36 are formed on the redistribution plane 38, thereby eliminating the need for an expensive, high-frequency compatible substrate for the circuit board 10. Figure 1 The substrate 12 in the middle. This also has the advantage that the electronic (NF) component 16 can be arranged on the upper side of the circuit board together with the high-frequency component 14. The package portion 40 with semiconductor chip and redistribution plane forms a so-called primary package, which can be implemented in different ways, such as by eWLB (embedded wafer-level ball grid array) or as a flip chip on an interposer. Since the molded body 20 is not connected to the semiconductor material of the high-frequency component in such a primary package, the material used for the molded body 20 does not need to be ion-reinforced.

[0029] Figure 3 and Figure 4 Showing according to Figure 2 Possible variations of the embodiments. In Figure 3 In this package, a redistribution plane 38 and microwave lines 34 are formed on the upper side, and the package is connected via bonding lines 42. Figure 4 In this package, the redistribution plane 44 is located on the underside of the package and is connected via solder balls 44 (e.g., in the form of a BGA (Ball Grid Array)). The high-frequency line 34 is located on the top side of the package and is formed by a so-called pad-on-package antenna. Alternatively, the package could be an eWLB or a CSP (Chip Size Package) with flip-chips on an interposer.

[0030] In yet another embodiment, the high-frequency component 14 is configured as an AoP (Antenna on Package) package. Different examples of this package are... Figures 5 to 7 As shown in the image.

[0031] exist Figure 5In this configuration, a high-frequency component 14 formed by a MMIC (bare chip) is mounted on the lower side of a multilayer interposer 46, which carries a plurality of antennas 48 on its upper side. These antennas are used to couple to a waveguide structure 22 and to connect to a semiconductor chip through a metallized through-hole 50 called a via.

[0032] exist Figure 6 In the middle, antenna 48 and MMIC are located on the upper side of intermediate plate 46.

[0033] exist Figure 7 In this configuration, the MMIC arranged on the intermediate plate 46 is modified with a package 52, on the upper side of which an antenna 48 is located. In this case, the antenna is connected to the high-frequency component 14 through a through-hole 53 (so-called through-mold via) and through the intermediate plate 46, the through-hole passing through the package 52.

[0034] The connection of this package is made through solder balls 44.

[0035] Figure 8 An embodiment is shown, which is consistent with the embodiment according to Figure 1 The embodiment differs in that the injection molding encapsulation of the high-frequency component 14 with plastic is performed in two steps. In the first step, the high-frequency component 14, mounted on the circuit board 10, is injection molded into the package 54. Then, in the second step, a molding body 20 is injection molded, which accommodates the circuit board 10 and the package 54 and forms the waveguide structure 22. This manufacturing method with two injection molding steps can also be similarly applied to the following embodiments in which the high-frequency component is a flip-chip MMIC or a wire-bonded MMIC. In the latter case, the bonding wires are then embedded in the package 54.

[0036] Figure 9 An embodiment is shown, which is consistent with the embodiment according to Figure 1 The embodiment differs in that the high-frequency component 14 (e.g., a bare chip MMIC) is injection molded over a molded body 20' made of a conductive molding compound, for example, over a conductive, non-ionic epoxy thermosetting material. The metallization 28 on the wall of the waveguide structure 22 can then be omitted.

[0037] Figure 10 One embodiment is shown in which a circuit board 10 having one or more high-frequency components 14 and a molded body 20 having a cover 30 form a module that forms only the high-frequency components of the radar sensor, while the remaining (NF) components 16 are arranged on a main circuit board 56, and then the main circuit board is equipped with the high-frequency module.

[0038] Figure 11One embodiment is shown in which a high-frequency component 14, such as an MMIC, is arranged on the underside of a circuit board 10 within the package. In this case, attachment to the waveguide structure 22 is achieved via a coaxial impedance transformer 58 that extends through the circuit board to its upper surface and is then connected to the waveguide structure 22 either indirectly via a high-frequency line 34 formed on the upper side of the circuit board or directly via a coupling structure 36.

[0039] Figure 12 An example of a radar sensor is shown, in which the high-frequency component 14 is a bonded MMIC on the upper side of a circuit board, similar to... Figure 8 The MMIC is injection molded and encapsulated by a package 54, which itself is embedded in the molded body 20. A cover 30' replaces the metal sheet cover 30 described so far, and is shown here separately from the molded body 20. The cover 30' is a sheet-like molded body made of plastic, having a metallized portion 60 on its underside, which is interrupted at certain locations by windows 62 to form radiation openings for microwaves. However, the plastic body of the cover does not puncture at these openings 62, but rather thins only to a relatively thin membrane 64, which closes the windows 62 to the outside. In this way, the cover 30' simultaneously forms an radome, a covering device that allows microwave radiation to pass through with almost no attenuation but prevents dust or corrosive media from penetrating the waveguide structure.

[0040] exist Figures 13 to 16 A variant of cover 30' is shown. Figure 13 In the cover, there is a plate-shaped core 66 made of plastic, which has metallized portions 60 on its entire outer surface. The radiation openings of the waveguide antenna are formed by windows 62 aligned with each other in the metallized portions on the opposite surface of the cover.

[0041] Figure 14 Another variant with an integrated radome is shown. However, the membrane 64 is located on the upper side of the plastic plate and covers the slits 68, which taper gradually toward the window 62 in the metallization 60 formed only on the lower side in cross-section.

[0042] exist Figure 15 In this embodiment, the slit 68 opens at the upper (outer) side and gradually tapers towards the membrane 64, which is formed on the lower side of the plastic block (plastic molded body) and covers the window 62 in the metallized portion. In this embodiment, the entire outer surface of the cover (except for the radiating opening) is formed with a relief 70, which forms an absorber structure 70 in the form of a grid of conical protrusions designed to suppress unwanted reflections on the surface of the radome.

[0043] at last, Figure 16A variant of the cover 32' with an integrated radome is shown, which is consistent with the design according to... Figure 15 A particularly distinctive variation is that the outer surface of the cover is formed with an embossed design 72 featuring a wide range of curved surfaces. This measure also serves to suppress unwanted reflections or deflect or scatter them in a harmless direction. Alternatively, the embossed design 72 can also form even more intricate absorber structures on the curved surfaces.

[0044] according to Figure 16 Another unique feature of the radome is that heating wires are embedded in the plastic body, forming a heating device 74 for the radome. This integrated heating device can resist the formation of a crust of ice or snow on the radome, thus preventing radar sensor blindness.

[0045] Figure 17 and Figure 18 The following embodiments are shown: In these embodiments, portions of the waveguide structure 22 are formed on opposite sides of the circuit board 10 in the molded body 20. The two sides of the molded body 20 can therefore be used for more complex distributor networks. Alternatively, waveguide antennas can also be formed on both sides of the molded body, allowing radar radiation to be emitted in opposite directions.

[0046] The connection between the portions of the waveguide structure 22 on the opposite side of the circuit board 10 can be formed in different ways, for example by connecting the waveguide 76 around the board 10 or by means of the through portion 78 passing through the circuit board.

[0047] In the example shown here, the circuit board 10 is equipped with high-frequency components 14 on both sides, which are connected to the distributor network via coaxial impedance transformers 58 and / or via planar high-frequency lines 34.

[0048] exist Figure 17 In this configuration, the distributor network also includes distributor bridges 80, by which some electronic components 16 can be bridged. The cavities forming the distributor bridges 80 are created during the injection molding of the molded body 20 and are also provided with metallized portions 28, just like the rest of the waveguide structure, and are then closed on both sides of the molded body 20 by caps 30.

[0049] exist Figure 18 The embodiments shown have waveguide distributor structures 80' and 82 that are not manufactured during injection molding of the molding body 20, but are constructed as individual waveguide elements. The circuit board 10 equips these waveguide elements and is subsequently injection molded together with the high-frequency component 14 by the material of the molding body 20. Distributor structure 80' is similar to... Figure 17The bridge distributor 80 is a bridge distributor, while the distributor structure 82 is a distributor chamber directly attached to the circuit board 10. In this example, the distributor chamber is coupled to one of the waveguides on the upper side of the circuit board via a coaxial impedance transformer 58.

[0050] Although according to Figure 17 The radar sensor has waveguide antennas in two mutually parallel planes (on opposite sides of circuit board 10), but it is also possible to implement a multi-plane antenna by forming waveguide antennas in multiple non-parallel planes. Figure 19 A simplified example is shown. On circuit board 10, a molded body 20" is sprayed onto one side, completely surrounding the high-frequency component that is not visible therein and forming a waveguide structure 22". This waveguide structure forms a distributor network that is coupled to the high-frequency component via a coupling structure 36" and directed to two subarrays 84, 86 of the waveguide antenna. The waveguide antenna and its distribution structure are open toward the outer surface 24" of the molded body 20". The outer surface 24" includes two non-parallel partial surfaces 24a, 24b that are adjacent to each other at an angle and each contains one of the subarrays 84, 86. The waveguide structure 22" is completed by a cover 30" injection-molded in a plastic part, which has a shape complementary to the outer surface 24" and has a metallization 60" on the underside that leaves only the radiation opening of the waveguide antenna.

Claims

1. A radar sensor having a high-frequency component (14) arranged on a circuit board (10) and a waveguide structure (22; 22") connected to the high-frequency component (14) via a coupling structure (36; 36"), characterized in that, The waveguide structure (22; 22") is formed in a molded body (20; 20', 20"), which is sprayed onto the portion of the circuit board (10) carrying the high-frequency component (14) by precise alignment of the circuit board (10) with the tool used to form the molded body (20; 20', 20"), wherein the circuit board (10) is generally encapsulated by the molded body (20) except for the connection unit (18) for connecting the plug.

2. The radar sensor according to claim 1, wherein the high-frequency component (14) is injection molded over the material of the molded body (20).

3. The radar sensor according to claim 1 or 2, wherein the waveguide structure (22; 22") forms at least one waveguide antenna.

4. The radar sensor according to any one of the preceding claims, wherein the waveguide structure (22) forms a distributor structure for connecting the high-frequency component (14) to the radar antenna.

5. The radar sensor according to any one of the preceding claims, wherein the high-frequency component (14) is injection molded over the material of the encapsulation portion (54) forming the high-frequency component, and wherein the encapsulation portion (54) itself is injection molded over the material of the molding body (20) in the radar sensor.

6. The radar sensor according to any one of the preceding claims, wherein the molded body (20') is composed of a conductive material.

7. The radar sensor according to any one of claims 1 to 5, wherein the waveguide structure (22; 22") has a cavity (26) open toward the outer surface (24; 24") of the molded body (20; 20"), and the inner wall of the cavity has a metallized portion (28), and the cavity is closed by a cover (30; 30") covering the outer surface (24; 24"), the cover having a metal layer at least on the side toward the molded body (20; 20").

8. The radar sensor according to claim 7, wherein the outer surface (24") of the molded body (20") has non-parallel partial surfaces (24a, 24b) forming a relief without side recesses, and wherein the cover (30") of the radar sensor has an integrally manufactured molded part having a metallic surface complementary to the outer surface (24").

9. The radar sensor according to any one of the preceding claims, wherein the cover (30') is a molded body made of plastic, the molded body having a metallized portion (60) on at least one side.

10. The radar sensor according to claim 9, wherein the molded body of the cover (30') forms the radome of the radar sensor.

11. The radar sensor according to claim 9 or 10, wherein the molded body of the cover (32') has an embossed (70; 72) on the non-metallized side.

12. The radar sensor according to claim 11, wherein the relief (70) is an absorber structure.

13. The radar sensor according to claim 11 or 12, wherein the relief (72) has an integrally curved surface with or without an absorber structure.

14. The radar sensor according to any one of claims 10 to 13, wherein at least a portion of the radome heating device (74) is integrated into the molded body of the cover (32').

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