Radar sensor with waveguide structure

Abstract

To provide a radar sensor which can be easily manufactured with low manufacturing tolerances and is robust against environmental influences.SOLUTION: A radar sensor is provided, comprising a high-frequency component (14) mounted on a circuit board (10) and a waveguide structure (22) connected to the high-frequency component (14) via a coupling structure (36). The waveguide structure (22) is formed in a mold (20') formed on a part of the circuit board (10) supporting the high-frequency component (14).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radar sensor having a high-frequency component disposed on a substrate and a waveguide structure coupled to the high-frequency component via a coupling structure. [Background technology]

[0002] DE 10 2014 208 389 A1 describes a radar sensor of the type in which the waveguide structure is a waveguide antenna array. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] DE102014208389A1 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION It is an object of the present invention to provide a radar sensor that can be manufactured simply with small manufacturing tolerances and is robust against environmental influences. [Means for solving the problem]

[0005] According to the present invention, this problem is solved by forming the waveguide structure in a molded body that is molded on a portion of the substrate that supports the high-frequency component.

[0006] When molding the molded body on the substrate, precise alignment between the substrate and the mold used to form the molded body allows the waveguide structure to be positioned and formed with narrow dimensional tolerances relative to the high-frequency component. At the same time, the material bond between the molded body and the substrate avoids the use of additional fastening means that could cause subsequent distortion of the product. The formation of a joint between the molded body and the substrate that is susceptible to corrosion is also avoided.

[0007] Advantageous modifications and embodiments of the invention are set out in the dependent claims.

[0008] In one embodiment, the high frequency component, or possibly the structure having multiple high frequency components, is located on the same side of the substrate as the waveguide structure, and the high frequency component or components are also overmolded with molding material. However, embodiments are also contemplated in which the high frequency component and the waveguide structure are on opposite sides of the substrate, and the coupling structure includes a penetration through the substrate. It is also contemplated that the substrate is overmolded on both sides with molding material, in which case the waveguide structure may be on both sides of the substrate.

[0009] The waveguide structure may form a waveguide antenna, an array of waveguide antennas, and / or a distribution network that connects multiple antennas to multiple high frequency components. Optionally, the waveguide structure may have multiple layers of waveguides, where different layers may be formed in successive steps during injection molding.

[0010] The molding can be made of a non-conductive material, such as a thermoplastic or thermosetting plastic, in which case only the walls of the waveguide have a conductive coating. In another embodiment, the molding can be made entirely of a conductive material, for example a plastic with a certain content of conductive particles, which make the material entirely conductive. In this regard, the material content and particle size of the conductive particles are selected so that sufficient conductivity is achieved even taking the skin effect into account.

[0011] In one embodiment, the waveguide structure has a hollow space that opens toward the outer surface of the molded body. In this case, this hollow space is closed by a cover with a conductive layer at least on the side facing the molded body. In the case of a waveguide antenna, the cover can have openings of suitable dimensions and shapes for emitting and receiving radar signals.

[0012] The cover may consist entirely of metal sheet or of plastic metallized on at least one side, in which case the cover may be a further moulding incorporating a radome and / or having reliefs to suppress unwanted microwave reflections.

[0013] These features may be advantageous although independent of the features of claim 1. Thus, a radar sensor is also disclosed which comprises a waveguide antenna formed in a base, the waveguide being formed by a hollow space opening towards the outer surface of the base, and a cover which completely or partly closes the hollow space with a conductive layer, the cover being formed by a molding incorporating a radome and / or having a relief on its outer surface.

[0014] Alternatively or additionally, the molding may incorporate a radome heater or at least one plug-in connector for connecting an external radome heater.

[0015] The outer surface of the molding on which the waveguide structures are formed can also have a relief, thereby forming, for example, a multi-faceted or conformal antenna array (i.e. the radiating surfaces of the antenna elements lie in planes inclined to one another or are part of a curved surface).If this relief on the outer surface is free of undercuts, the cover can be a one-piece molding with a surface complementary to the relief.

[0016] In the following, exemplary embodiments are explained in more detail on the basis of the drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic cross-sectional view of a radar sensor according to the present invention; [Figure 2] 10A-10C are cross-sectional views of various variations of another embodiment of the present invention. [Figure 3] 10A-10C are cross-sectional views of various variations of another embodiment of the present invention. [Figure 4] 10A-10C are cross-sectional views of various variations of another embodiment of the present invention. [Figure 5] 1 is a schematic cross-sectional view of a high-frequency component that can be used in a radar sensor according to the present invention. [Figure 6] 1 is a schematic cross-sectional view of a high-frequency component that can be used in a radar sensor according to the present invention. [Figure 7] 1 is a schematic cross-sectional view of a high-frequency component that can be used in a radar sensor according to the present invention. [Figure 8] 4 is a cross-sectional view of a radar sensor according to a further exemplary embodiment of the present invention; [Figure 9] 4 is a cross-sectional view of a radar sensor according to a further exemplary embodiment of the present invention; [Figure 10] 4 is a cross-sectional view of a radar sensor according to a further exemplary embodiment of the present invention; [Figure 11] 4 is a cross-sectional view of a radar sensor according to a further exemplary embodiment of the present invention; [Figure 12] 1 is an exploded cross-sectional view of a radar sensor having a waveguide structure closed by a cover. [Figure 13] 10A-10C are cross-sectional views of various embodiments of the cover. [Figure 14] 10A-10C are cross-sectional views of various embodiments of the cover. [Figure 15] 10A-10C are cross-sectional views of various embodiments of the cover. [Figure 16] 10A-10C are cross-sectional views of various embodiments of the cover. [Figure 17] 4 is a cross-sectional view of a radar sensor according to a further exemplary embodiment of the present invention; [Figure 18] 4 is a cross-sectional view of a radar sensor according to a further exemplary embodiment of the present invention; [Figure 19] FIG. 10 is a perspective exploded view of a radar sensor according to a further exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The radar sensor shown in cross section in FIG. 1 comprises a substrate 10 with a high-frequency carrier substrate 12 on its upper surface and high-frequency components 14. The high-frequency components 14 can be, for example, MMIC (Monolithic Microwave Integrated Circuit) packages (monolithic microwave integrated circuits with plastic housings). On its lower surface, the substrate 10 carries further electronic components 16 (e.g., ICs, SMDs (Surface Mounted Devices)) and contact units 18 for connecting plugs in a known manner. The entire substrate 10, including the components arranged thereon (except for some of the contact units 18), is overmolded with a molding 20 made of a non-conductive plastic, preferably a thermosetting plastic, but optionally a thermoplastic plastic. A waveguide structure 22 is formed on the upper surface of the molding 20. This waveguide structure 22 has several hollow spaces 26 opening toward the outer surface 24 of the molding, the walls of which are made conductive by a metal coating 28. A cover 30 is attached to the outer surface 24 by any known joining technique, such as welding or adhesive bonding. The cover 30 covers the entire hollow space 26 and is in electrical contact with the metal coating 28 of the hollow space 26, allowing the hollow space 26 to function as a waveguide. In some areas of the hollow space 26, the cover 30 has openings 32 that can emit and / or receive microwaves, thereby allowing the hollow space to function as a waveguide antenna. The remaining waveguides of the waveguide structure 22 form a distribution network through which radar signals generated in the high-frequency component 14 are transmitted to the waveguide antenna and / or radar signals received by the waveguide antenna are transmitted to the high-frequency component 14. To signal-couple the high-frequency component 14 to the waveguide structure 22, a high-frequency line 34, such as a microstrip line, is formed on the carrier substrate 12 and is coupled to one of the waveguides via a coupling structure 36. It will be appreciated that a radar sensor may include multiple high frequency components 14 on the same substrate 10, each coupled to a waveguide antenna through an associated distribution network.

[0019] In manufacturing the radar sensor, the substrate 10 is first loaded with the high-frequency components and the remaining electronic components as well as the contact unit 18, and then overmolded with a molding 20, with care taken to ensure precise alignment of the mold with respect to the substrate using alignment marks (not shown). After demolding, a metal coating 28 is provided on the walls of the hollow space 26 (except for the free end of the connecting structure 36), and finally the hollow space is closed by a cover 30.

[0020] In the illustrated example, the cover 30 is simply formed from a metal plate, but in other embodiments, the cover may be a metalized plastic plate or a metalized plastic molding.

[0021] FIG. 2 shows a modified exemplary embodiment in which the high-frequency component 14 is an MMIC in the form of an unpackaged semiconductor chip (bare chip), which is disposed on a redistribution surface 38 and overmolded with a package 40, which also constitutes part of the coupling structure 36. In this case, the high-frequency lines 34 for coupling to the coupling structure 36 are formed on the redistribution surface 38, eliminating the need for an expensive high-frequency substrate for the substrate 10 (substrate 12 in FIG. 1). This also has the advantage that the electronic (NF) component 16 may be disposed on the upper surface of the substrate together with the high-frequency component 14. The package 40, together with the semiconductor chip and the redistribution surface, constitutes a so-called primary package, which can be realized in various ways, for example, by an embedded wafer-level ball grid array (eWLB) or as a flip chip on an interposer. In such a primary package, the molding 20 does not come into contact with the semiconductor material of the high-frequency component, so the material used for the molding 20 does not need to be ion-free.

[0022] 3 and 4 show possible variants of the exemplary embodiment according to FIG. 2. In FIG. 3, the rewiring plane 38 and the microwave lines 34 are formed on the top of the package and the package is contacted by bonding wires 42. In FIG. 4, the rewiring plane 38 is present on the bottom of the package and contact is made by solder balls 44 (for example in the form of a BGA (Ball Grid Array)). The high-frequency lines 34 are present on the top side of the package and are formed by so-called pad-on-package antennas. Alternatively, the package may be a CSP (Chip Size Package) with an eWLB or a flip chip on an interposer.

[0023] In yet another embodiment, the high-frequency component 14 is configured as an AoP package (Antenna on Package). Various examples of such packages are shown in FIGS.

[0024] In Figure 5, a high-frequency component 14 formed by an MMIC (bare chip) is attached to the underside of a multilayer interposer 46, and the multilayer interposer 46 supports multiple antennas 48 on its upper surface, which serve to couple to the waveguide structure 22 and are coupled to the semiconductor chip through metal-coated through-holes 50 called vias.

[0025] In FIG. 6, the antenna 48 and the MMIC are on the top surface of the interposer 46 .

[0026] 7, the MMIC disposed on the interposer 46 is formed together with a package 52, and the antenna 48 is present on the top surface of the package 52. In this case, the antenna is coupled to the high-frequency component 14 via a through-hole 53 that passes through the package 52, a so-called through-mold via, and the interposer 46.

[0027] Contact to the package is made via respective solder balls 44.

[0028] 8 shows an exemplary embodiment that differs from the exemplary embodiment according to FIG. 1 in that the overmolding of the high-frequency component 14 in plastic is performed in two steps. In a first step, the high-frequency component 14 mounted on the substrate 10 is overmolded with a package 54, after which in a second step a molding 20 is injection molded. This molding 20 contains the substrate 10 and the package 54 and forms the waveguide structure 22. This manufacturing method with two injection molding steps can also be applied in embodiments in which the high-frequency component is a flip-chip MMIC or a MMIC contacted by wire bonding. In the latter case, bonding wires are then embedded in the package 54.

[0029] 9 shows an exemplary embodiment which differs from the exemplary embodiment according to FIG. 1 in that the high-frequency component 14 (e.g. a bare-chip MMIC) is overmolded with a molding 20′ made of a conductive molding material, for example a conductive ion-free epoxy-based thermosetting resin. In this case, the metal coating 28 on the wall of the waveguide structure 22 can be eliminated.

[0030] FIG. 10 shows an exemplary embodiment in which the substrate 10 with the high frequency component 14 or multiple high frequency components and the molded body 20 with the cover 30 constitute a module forming only the high frequency part of the radar sensor, while the remaining (NF) components 16 are placed on a main board 56, on which the high frequency module is then mounted.

[0031] 11 shows an exemplary embodiment in which a high-frequency component 14, such as an MMIC, is disposed within a package on the underside of a substrate 10. In this case, coupling to a waveguide structure 22 is via a coaxial impedance transformer 58, which passes through the substrate and leads to the upper surface of the substrate, where it is coupled to the waveguide structure 22 either indirectly via a high-frequency line 34 formed on the upper surface of the substrate, or directly via a coupling structure 36.

[0032] FIG. 12 shows a radar sensor in which the high-frequency component 14 is an MMIC bonded to the upper surface of the substrate, and the MMIC is overmolded with a package 54, as in FIG. 8, with the package 54 also embedded in the molding 20. Instead of the metal plate-shaped cover 30 of the previously described embodiments, a cover 30' is shown separated from the molding 20. The cover 30' is a plastic plate-shaped molding with a metal coating 60 on its underside, interrupted at several points by windows 62 that form microwave radiation openings. However, the plastic body of the cover is not perforated by the openings 62, but is formed into a relatively thin membrane 64 that seals the cover 62 from the outside. In this way, the cover 30' simultaneously functions as a radome, i.e., it allows microwave radiation to pass through it substantially unattenuated, while preventing the intrusion of dirt and corrosive media into the waveguide structure.

[0033] Modifications of the cover 30' are shown in Figures 13 to 16. In Figure 13, the cover has a plate-like plastic core 66 which has a metal coating 60 over its entire outer surface. The radiating opening for the waveguide antenna is formed by aligned windows 62 in the metal coating on opposing faces of the cover.

[0034] 14 shows a further variation incorporating a radome, except that here a membrane 64 is on top of the plastic plate and covers an opening 68 that tapers in cross section to a window 62 in the metal coating 60 formed only on the underside.

[0035] 15, the opening 68 is open at the top (external surface) and tapers towards the membrane 64, which here is formed on the underside of a plastic block (plastic molding) and covers the metallized window 62. In this embodiment, the entire outer surface of the cover, except for the radiation opening, forms a relief 70, which forms an absorber structure 70 in the form of a grid of conical protrusions, which suppress undesired reflections on the surface of the radome.

[0036] Finally, Figure 16 shows a variant of the cover 32' incorporating a radome, which differs from the variant according to Figure 15, inter alia, in that the outer surface of the cover is formed with a more extensive curved relief 72. This measure also serves to suppress unwanted reflections or deflect or scatter them in harmless directions. Optionally, the curved relief 72 may form an even finer absorber structure.

[0037] 16 is further characterized by the fact that the plastic body contains an embedded heating wire, which forms a radome heater 74. Such an embedded heater counteracts the formation of a snow or ice crust on the radome and thus blinds the radar sensor.

[0038] 17 and 18 show an exemplary embodiment in which components of the waveguide structure 22 are formed on opposite sides of the substrate 10 within the molding 20. In this way, both sides of the molding 20 can be utilized for more complex distribution networks. Optionally, waveguide antennas can also be formed on both sides of the molding, so that radar waves can be radiated in opposite directions.

[0039] Interconnections between components of the waveguide structure 22 on opposite sides of the substrate 10 can be made in a variety of ways, for example by coupling waveguides 76 that bypass the substrate 10 or using through holes 78 that pass through the substrate.

[0040] In the example shown, the substrate 10 has high frequency components 14 mounted on both sides, and these high frequency components 14 are coupled to the distribution network via coaxial impedance transformers 58 and / or planar high frequency lines 34.

[0041] 17, the distribution network also includes distribution bridges 80 that can bridge between some of the electronic components 16. The hollow spaces that make up the distribution bridges 80 are formed during injection molding of the molded body 20 and, like the rest of the waveguide structure, have a metal coating 28, and are then closed on both sides of the molded body 20 by covers 30.

[0042] The exemplary embodiment shown in Figure 18 includes waveguide distribution structures 80', 82. These waveguide distribution structures 80', 82 are not formed during the injection molding of the molded body 20, but are formed as separate waveguide elements that are mounted on the substrate 10, and then the waveguide elements and substrate 10, along with the high frequency components 14, are overmolded with the material of the molded body 20. The distribution structure 80' is a bridge divider similar to the bridge divider 80 of Figure 17, while the distribution structure 82 is a distribution chamber that directly interfaces with the substrate 10 and is coupled to one of the waveguides on top of the substrate via the coaxial impedance transformer 58 in this example.

[0043] While the radar sensor according to FIG. 17 has waveguide antennas in two parallel planes (on opposite sides of the substrate 10), embodiments are also possible in which the waveguide antenna is formed in multiple non-parallel planes, forming a multi-faceted antenna. A simple example is shown in FIG. 19. A molding 20″ is injection molded on one side of the substrate 10, completely enclosing the high-frequency components (not visible here) and forming a waveguide structure 22″. This waveguide structure forms a distribution network that is connected to the high-frequency components via a coupling structure 36″ and leads to two sub-arrays 84, 86 of the waveguide antenna. The waveguide antenna and the distribution structure open towards an outer surface 24″ of the molding 20″. This outer surface 24″ includes two non-parallel sub-surfaces 24a, 24b that are adjacent to each other at an angle and each include one of the sub-arrays 84, 86. The waveguide structure 22'' is complemented by a cover 30'' which is integrally injection molded from a plastic material, the cover 30'' having a shape complementary to the outer surface 24'' and having a metal coating 60'' on its underside which is open only at the radiating opening of the waveguide antenna. [Explanation of symbols]

[0044] 10 Substrate 12 Carrier substrate 14 High-frequency components 16 Electronic Components 26 Hollow space 32 Opening 42 Bonding Wire 44 solder balls 46 Interposer 48 Antenna 56 Main board 58 Coaxial Impedance Transformer 66 Core 76 Coupled Waveguide 78 Through Hole

Claims

1. a high-frequency component (14) disposed on a substrate (10); a waveguide structure (22; 22'') coupled to the high-frequency component (14) via a coupling structure (36; 36''); the waveguide structure (22; 22″) is formed in a molded body (20; 20′, 20″) molded on a portion of the substrate (10) that supports the high-frequency component (14); The high-frequency component (14) is overmolded with the material of the molding (20). A radar sensor characterized by:

2. 2. The radar sensor according to claim 1, wherein the substrate (10) is entirely overmolded with the molding (20) except for a plug connection (18).

3. A high-frequency component (14) arranged on a substrate (10); a waveguide structure (22; 22'') coupled to the high-frequency component (14) via a coupling structure (36; 36''); the waveguide structure (22; 22″) is formed in a molded body (20; 20′, 20″) molded on a portion of the substrate (10) that supports the high-frequency component (14); The high-frequency component (14) is overmolded with a material constituting a package (54) of the high-frequency component, and the package (54) is also overmolded with a material of the molding (20).

4. 4. The radar sensor according to claim 1, wherein the molded body (20') is made of an electrically conductive material.

5. A high-frequency component (14) arranged on a substrate (10); a waveguide structure (22; 22'') coupled to the high-frequency component (14) via a coupling structure (36; 36''); the waveguide structure (22; 22″) is formed in a molded body (20; 20′, 20″) molded on a portion of the substrate (10) that supports the high-frequency component (14); The waveguide structure (22; 22'') has a hollow space (26) that opens toward the outer surface (24; 24'') of the molded body (20; 20''), the inner wall of the hollow space (26) has a metal coating (28), and the hollow space is closed by a cover (30; 30'; 30'') that covers the outer surface (24; 24''), and the cover (30; 30'; 30'') has a metal layer at least on the side facing the molded body (20; 20'').

6. 6. The radar sensor of claim 5, wherein the outer surface (24'') of the molded body (20'') has non-parallel partial surfaces (24a, 24b) that form a relief without undercuts, and the cover (30'') comprises an integrally formed molded member, the molded member having a metal surface that is complementary to the outer surface (24'').

7. 7. The radar sensor according to claim 5, wherein the cover (30') is a molded body made of plastic, the molded body having a metal coating (60) on at least one side.

8. 8. The radar sensor of claim 7, wherein the molding of the cover (30') is a radome of the radar sensor.

9. 9. A radar sensor according to claim 7 or 8, wherein the molding of the cover (32') has a relief (70; 72) on the side not having the metal coating.

10. 10. The radar sensor of claim 9, wherein the relief (70) is an absorber structure.

11. 11. A radar sensor according to claim 9 or 10, wherein the relief (72) has a generally curved surface with an absorber structure or a generally curved surface without an absorber structure.

12. 12. The radar sensor of claim 8, wherein at least a portion of a radar dome heater (74) is incorporated into the molding of the cover (32').

13. A radar sensor as described in any one of claims 1 to 12, wherein the waveguide structure (22; 22'') forms at least one waveguide antenna.

14. A radar sensor described in any one of claims 1 to 13, wherein the waveguide structure (22) forms a distribution structure for coupling the high-frequency component (14) to a radar antenna.

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