Radar sensor with laser-soldered waveguide antenna and method for the production thereof

Abstract

The present invention provides a radar sensor which comprises a waveguide antenna, a printed circuit board and a chip, wherein the waveguide antenna and the printed circuit board are mechanically and conductively connected to one another by at least one laser-soldered connection. The present invention also relates to a method for producing a radar sensor, said method comprising the following steps: providing a waveguide antenna; providing a printed circuit board; providing a chip; joining the chip to the printed circuit board; mechanically and conductively connecting the waveguide antenna to the printed circuit board by at least one laser-soldered connection.

Description

[0001] R. 413958

[0002] - 1 -

[0003] Description

[0004] title

[0005] Radar sensor with laser-soldered waveguide antenna and method for its manufacture

[0006] State of the art

[0007] The present invention relates to a radar sensor with a laser-soldered waveguide antenna and a method for its manufacture.

[0008] Radar sensors are used to implement comfort features such as adaptive cruise control and safety features such as emergency brake assist. These sensors emit high-frequency radar beams via an antenna structure and receive the beams reflected by objects. The detected objects can be stationary or moving. Using the received radar beams, the distance and direction (angle) to the object can be calculated. The relative speed of an object to the radar sensor can also be determined. Typical radar sensors operate in a frequency range between 76 and 81 GHz.

[0009] In the future, waveguide antennas will be increasingly used as radar antennas because they offer low power loss and high bandwidth. Traditionally, the waveguide antenna is connected to a printed circuit board and receives radar signals via electrical components on the board. However, designing the waveguide antenna as a separate component creates a new interface in the sensitive high-frequency transmission path between the circuit board and the waveguide antenna. The connection concept between the waveguide antenna and the circuit board has a significant impact on R. 413958.

[0010] - 2 - the overall performance of the system. An inadequate connection can, for example, lead to unwanted electromagnetic interference.

[0011] In EP 4097796 A1, EBG (Electromagnetic Bandgap) structures arranged around the waveguide channels of a waveguide antenna are used as additional structures to prevent or reduce such unwanted electromagnetic leakage.

[0012] Disclosure of the invention

[0013] According to the invention, a radar sensor with a laser-soldered waveguide antenna with the features of claim 1 and a method for manufacturing the radar sensor with a laser-soldered waveguide antenna with the features of claim 11 are provided.

[0014] The radar sensor according to the invention comprises a waveguide antenna, a circuit board, and a chip, wherein the waveguide antenna and the circuit board are mechanically and conductively connected to each other by at least one laser solder connection.

[0015] One aspect of the invention lies in a laser soldering connection between the waveguide antenna and the circuit board, enabling a reliable and robust assembly of the two components while simultaneously optimizing the performance and manufacturing costs of the radar sensor. Furthermore, the waveguide antenna mounting concept is space-saving.

[0016] As explained in more detail below, laser solder joints are known for being a reliable and robust type of connection. Laser soldering allows for the production of high-quality, reliable solder joints with a lower risk of bridging or spattering, which is crucial for ensuring long-term reliability and robustness. R. 413958

[0017] - 3 -

[0018] Unlike conventional fasteners such as screws and clamps at the interface between the waveguide antenna and the circuit board, a laser-soldered connection offers an air-gap-free connection. The presence of air gaps can lead to electromagnetic leakage. Therefore, laser-soldered connections can create an air-gap-free connection, optimizing radar sensor performance and saving space, as no additional structures are required to compensate for potential unwanted electromagnetic leakage.

[0019] Furthermore, the inventive method for manufacturing a radar sensor is characterized by the following steps:

[0020] - Provision of a waveguide antenna;

[0021] - Providing a printed circuit board;

[0022] - Providing a chip;

[0023] - Assembling the chip with the circuit board;

[0024] - mechanical and conductive connection of the waveguide antenna to the circuit board by at least one laser soldering connection.

[0025] Another aspect of the invention lies in a laser soldering process for connecting the waveguide antenna and the circuit board, which reduces the manufacturing costs of the radar sensor and at the same time enables a safe mounting concept for the waveguide antenna.

[0026] As explained in more detail below, the described laser soldering process is based on a cost-effective and established standard soldering method. Furthermore, laser soldering is a non-contact process that minimizes the thermal impact on surrounding areas such as the printed circuit board and the waveguide antenna. This makes the joining process safer, with a minimal risk of damaging the radar sensor components, such as minimizing thermal warping due to differing coefficients of thermal expansion. R. 413958

[0027] - 4 -

[0028] Advantageous designs and further developments result from the additional sub-claims as well as from the description with reference to the figures.

[0029] In one embodiment, the printed circuit board (PCB) includes at least one through-hole or a tabulated zone, both configured to connect the PCB to the waveguide antenna with a connecting element comprising at least one screw or clip, and the waveguide antenna includes at least one screw zone or sleeve, both configured to connect the waveguide antenna to the PCB. Using only a single laser solder connection between the waveguide antenna and the PCB results in a space-saving integration of the waveguide antenna, as it does not require a specific area on the PCB or on the waveguide antenna for a conventional connecting element.

[0030] In a preferred embodiment, the waveguide antenna has at least one waveguide channel with at least one metallized wall, and the at least one laser solder joint is located in close proximity to the at least one wall of the waveguide channel to together form a continuous smooth wall. The strategic placement of the laser solder joint offers significant advantages for improving the performance of the radar sensor. By creating a continuous and air-gap-free interface between the circuit board and the waveguide antenna, this connection configuration optimizes signal transmission and reception while simultaneously ensuring a robust waveguide antenna assembly.

[0031] In a preferred embodiment, the at least one laser solder joint is a narrow strip, preferably extending within 1 mm or less from the at least one wall of the waveguide channel. This conductive connection between the waveguide antenna and the printed circuit board is the simplest. This connection configuration reflects reduced manufacturing complexity while maintaining the performance of the waveguide antenna. R. 413958

[0032] - 5 -

[0033] According to a preferred embodiment, at least one means for transmitting and receiving microwave signals from the chip to the waveguide antenna comprises at least one or more plated vias arranged in the printed circuit board (PCB) or a high-frequency transmission line with a radiating element arranged on the PCB. The radar sensor has various configurations for microwave signal propagation. Despite these different arrangements, the laser soldered connection between the waveguide antenna and the PCB is maintained. This consistency underscores the adaptability of the laser-soldered connection method and demonstrates its effectiveness and flexibility in various radar sensor designs.

[0034] In a preferred embodiment, additional compensation structures configured for transmitting and receiving microwave signals are omitted, and the additional compensation structure comprises at least one electromagnetic bandgap (EBG) structure. The strategic omission of EBG structures offers a significant advantage in terms of spatial efficiency. This configuration allows for a more compact integration of the waveguide antenna. By eliminating these EBG structures, the radar sensor achieves a more space-saving configuration without compromising antenna performance.

[0035] In a preferred embodiment, the waveguide antenna is mounted on one side of the circuit board and the chip on an opposite side of the circuit board. The at least one means for transmitting and receiving microwave signals from the chip to the waveguide antenna comprises one or more plated vias that are directly connected to the at least one waveguide channel via the laser solder joint to form a continuous electrical connection. A continuous conductive connection between the waveguide channel and the vias results in optimal Rc. 413958

[0036] - 6 -

[0037] Radar performance, in particular by minimizing signal attenuation, reflection and coupling.

[0038] In a preferred embodiment, the waveguide antenna and the chip are mounted on the same side of the circuit board, and the at least one means for transmitting and receiving the microwave signals from the chip to the waveguide antenna comprises at least one high-frequency transmission line with a radiating element arranged on the circuit board. An integrated chip with the waveguide antenna offers the advantage of a space-saving waveguide antenna structure.

[0039] In a preferred embodiment, the laser solder joint comprises at least one thermally and electrically conductive material. This material facilitates heat dissipation, which is essential for good radar sensor performance, and simultaneously establishes a continuous electrically conductive connection between the circuit board and the waveguide antenna.

[0040] In a preferred embodiment, the waveguide antenna comprises at least one standard plastic or a thermoplastic material. The use of such a material makes it possible to reduce the production costs of the radar sensor.

[0041] According to a preferred embodiment, the process step of mechanically and conductively connecting the waveguide antenna to the circuit board is characterized by the following steps:

[0042] - Applying solder paste to the circuit board,

[0043] - Mounting the waveguide antenna on the circuit board so that at least one waveguide channel of the waveguide antenna is located in the immediate vicinity of the soldering paste,

[0044] - selective heating of the solder paste using at least one focused laser beam designed so that it does not touch the waveguide antenna and the circuit board, R. 413958

[0045] - 7 -

[0046] - Forming at least one laser solder joint during the cooling of the solder paste, which is located in the immediate vicinity of at least one waveguide channel of the waveguide antenna.

[0047] This process step requires an established standard laser soldering process, which enables an advantageously simple implementation of the present invention.

[0048] In a preferred embodiment, the process step of mechanically and conductively connecting the waveguide antenna to the printed circuit board takes place before or after a connection between at least one layer of the waveguide antenna and one or more other layers of the waveguide antenna. The connection between the layers of the waveguide antenna is made by soldering, preferably by laser soldering. The implementation of laser soldering processes for various interfaces beyond the interface between the printed circuit board and the waveguide antenna demonstrates the versatility of the soldering process.

[0049] In a preferred embodiment, the chip is joined to the circuit board either before or after the mechanical and conductive connection of the waveguide antenna to the circuit board. Laser soldering technology demonstrates its adaptability through various implementation solutions that enable different radar sensor configurations and mounting approaches.

[0050] In a preferred embodiment, the laser soldering connection between the printed circuit board and the waveguide antenna is performed by emitting the focused laser beam through the at least one waveguide channel, through at least one or more plated vias of the printed circuit board, or transversely between the printed circuit board and the waveguide antenna. The various options for focusing the laser beam offer the advantage that manufacturers can adapt the manufacturing process for different radar sensor configurations, demonstrating the flexibility of the laser soldering process. Furthermore, the laser soldering process provides an excellent solution for joining components that are difficult to access, demonstrating the suitability of this joining method for complex assemblies. This is particularly advantageous R. 413958.

[0051] - 8 - when connecting elements between printed circuit boards and waveguide antennas that are difficult to reach using conventional soldering methods.

[0052] The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures. These show:

[0053] Fig. 1 shows a schematic representation of a radar sensor with a laser-soldered waveguide antenna according to an embodiment of the present invention.

[0054] Fig. 2a shows a schematic representation of a radar sensor with a laser-soldered waveguide antenna according to a further embodiment of the present invention.

[0055] Fig. 2b shows a schematic representation of a high-frequency transmission line with a radiating element in a waveguide channel of a waveguide antenna in a top view according to an embodiment of the present invention.

[0056] Figs. 3a and 3b show a schematic representation of a manufacturing process for a radar sensor in which a laser soldering process is carried out to connect a waveguide antenna to a circuit board, according to an embodiment of the present invention.

[0057] Figs. 4a and 4b show a schematic representation of a manufacturing process for a radar sensor in which a laser soldering process is carried out to connect a waveguide antenna to a circuit board, and a laser soldering process is used to connect several layers of the waveguide antenna, according to a further embodiment of the present invention.

[0058] Fig. 5 shows a schematic representation of a manufacturing process for a radar sensor in which a laser soldering process is carried out to create an R. 413958

[0059] - 9 -

[0060] to connect a waveguide antenna to a circuit board, according to a further embodiment of the present invention.

[0061] Fig. 6 shows a schematic flowchart of various assembly orders for the manufacture of a radar sensor 1 according to an embodiment of the present invention.

[0062] The accompanying figures are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain the principles and concepts of the invention. Other embodiments and many of the advantages mentioned will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale.

[0063] In the figures of the drawing, identical, functionally equivalent and similarly acting elements, features and components - unless otherwise stated - are each provided with the same reference symbols.

[0064] Fig. 1 shows a cross-section of a radar sensor 1 with a laser-soldered waveguide antenna 2 according to an embodiment of the present invention. The radar sensor 1 can comprise at least one laser-soldered waveguide antenna 2, a circuit board 3, a chip 11, and a housing 13.

[0065] The PCB 3 is a printed circuit board or other substrate on which the waveguide antenna 2 and the chip 11 can be mounted. The PCB 11 can be a standard printed circuit board made of a flat, laminated composite material of non-conductive carrier materials with one or more layers of copper circuitry. In Fig. 1, the PCB 3 can have at least one surface 3' for mounting the waveguide antenna 2 and an opposing surface 3" for mounting the chip 11. A thermally and electrically conductive material 20, such as a metal, e.g., a copper alloy, can cover at least part of the surfaces 3' and 3" of the PCB 3. The PCB 3 can be connected between the surfaces 3' and 3" of the PCB 3.

[0066] - 10 -

[0067] 3" have several clad vias 6. The clad vias 6 are used as waveguide feedthroughs. The multi-clad vias 6 in Fig. 1 are holes extending through the entire thickness of the circuit board 3, but they can also be buried and blind-clad vias 6, arranged one above the other or not. The multi-clad vias 6 can be filled with either air or dielectric material (e.g., FR4 circuit board material) and comprise a thermally and electrically conductive material 20, such as a metal, e.g., a copper alloy, which can cover the inner surface(s) of the multi-clad vias 6. The cross-section of the clad vias 6 can be rectangular. In other embodiments, the cross-section of the clad vias 6 can form an approximately square, oval, trapezoidal, or circular opening.Openings with constrictions in the middle of the channel (so-called ridged or double-ridged waveguides) are also common. In other embodiments, a microstrip structure can also be arranged on the circuit board 3, which can be combined with the plated vias 6 for the transmission of high-frequency signals.

[0068] Chip 11 generates high-frequency signals that are transmitted to the waveguide antenna structure and receives high-frequency signals from the waveguide antenna structure. Chip 11 also processes the received high-frequency signals for further analysis. Chip 11 can be, for example, a standard integrated circuit (IC), a monolithic microwave integrated circuit (MMIC), or a microprocessor. The chip can be connected to the 3" surface of the printed circuit board (PCB) 3 via a ball grid array (BGA) 19. The thermally and electrically conductive material 20 can cover the 3" surface above chip 11. In another embodiment, the thermally conductive material 20 does not cover the surface of the PCB 3 above chip 11 in order to avoid interfering with the connection between chip 11 and PCB 3.The chip 11 can comprise several launcher / radiating structures 12 that serve as a transition between the chip 11 and the waveguide antenna 2 to efficiently couple electromagnetic waves from the planar chip 11 into the three-dimensional waveguide antenna 2. By using a launcher 12 that is directly integrated into the chip R. 413958.

[0069] Since the package of chip 11 is integrated, routing on the printed circuit board (PCB) is eliminated, which can cause additional insertion loss and consume PCB space. The launchers 12 can be correctly aligned with the respective plated vias 6 and the respective waveguide channels 5 of the waveguide antenna 2 to avoid power losses due to mismatches and to reduce potential electromagnetic leakage. In Fig. 1, the launcher 12 can be a launcher on package (LoP) or a launcher in package (LiP).

[0070] The waveguide antenna 2 can be an injection-molded antenna made of standard plastic or thermoplastic, which may also have a metal coating made of an aluminum alloy, stainless steel, a copper alloy, or other metal alloys. Alternatively, it can also be made directly of metal. The waveguide antenna 2 can consist of several layers 7, 8 running parallel to the surface 3' and 3" of the circuit board 3. The layers 7, 8 can be connected to each other by soldering or another joining method. Furthermore, the waveguide antenna 2 can include several waveguide channels 5 that guide the electromagnetic waves from the chip 11 to the radiator elements (not shown here) or from the radiator elements to the chip 11. The multiple waveguide channels 5 can be arranged through the layers 7 and 8 to form air-filled channels with a zigzag shape, but they can also have an approximately rectangular shape.The cross-section of the waveguide channels 5 can have an approximately rectangular shape. In other embodiments, the cross-section of the waveguide channels 5 can form an approximately square, oval, trapezoidal, or circular opening. The waveguide channels 5 can have a metallized wall 5'. In Fig. 1, the waveguide channels 5 can comprise at least a portion of the air-filled channel that forms a certain angle, more precisely a perpendicular angle, with the layers 7, 8 of the waveguide antenna 2. This transverse portion 5" of the waveguide channels 5 can have at least one inlet 5"' facing the surface 3' of the circuit board 3. In Fig. 1, the inlet 5"' can be for each of the R. 413958.

[0071] - 12 -

[0072] Waveguide channels 5 should be aligned directly above the respective plated vias 6 and above the respective launchers 12.

[0073] The waveguide antenna 2 is attached to the circuit board 3 via at least one laser solder joint 4. In Fig. 1, several laser solder joints 4 are arranged between the waveguide antenna 2 and the surface 3' of the circuit board 3, directly adjacent to the entrance 5"' of the waveguide channels 5. The laser solder joints 4 are narrow strips that completely surround the entrance 5"' of the waveguide channels 5, forming a continuous and preferably seamless wall with the metallized walls 5" of the waveguide channels 5. By creating a continuous and air-gap-free interface between the circuit board 3 and the waveguide antenna 2, the design of the connection optimizes signal transmission and reception while simultaneously ensuring a robust waveguide antenna assembly.The laser solder joints 4 can be limited in the transverse direction of the printed circuit board 3, so that the laser solder joints 4 form narrow solder strips that preferably extend within 1 mm or less from the walls 5" of the waveguide channels 5'. These soldered narrow strips are preferably arranged between a solderable surface of the waveguide antenna 2 and a solderable surface 18 of the printed circuit board 3.

[0074] The laser solder joints 4 define the distance between the circuit board 3 and the waveguide antenna 2. In other embodiments, in addition to the laser solder joints 4, further laser solder joints or laser solder balls (not shown here) can be arranged between the waveguide antenna 2 and the surface 3' of the circuit board 3 in outer areas to ensure a secure mechanical connection and a corresponding distance between the waveguide antenna 2 and the circuit board 3. Spacers (not shown here) can also be attached to the waveguide antenna in the outer areas between the waveguide antenna 2 and the surface 3' of the circuit board 3 to adjust the distance between the waveguide antenna 2 and the circuit board 3 in these outer areas. R. 413958

[0075] - 13 -

[0076] In Fig. 1, the laser solder joints 4 between the waveguide antenna 2 and the surface 3' of the printed circuit board 3 are arranged such that they directly adjoin the multi-clad vias 6 of the printed circuit board 3 and the respective inputs 5"' of the waveguide channels 5', so that the multi-clad vias 6 are aligned with the waveguide channels 5 during the connection process. Thus, the wall of the clad vias 6, the respective laser solder joints 4, and the respective walls 5" of the waveguide channels 5 form a continuous and preferably seamless wall. This configuration enables a smooth transition from the chip 11 to the waveguide antenna 2 and minimizes losses due to reflection and scattering while simultaneously matching the impedance of the waveguide antenna 2 to the chip 11. However, the shape of the waveguide channels 5 and the clad vias 6, as well as their orientation, can also differ if this is advantageous, for example, for manufacturing reasons.

[0077] Fig. 2a shows a cross-section of a radar sensor 1 with a laser-soldered waveguide antenna 2 according to a further embodiment of the present invention. Similar to Fig. 1, the radar sensor 1 can comprise at least one laser-soldered waveguide antenna 2, a circuit board 3, a chip 11, and a housing 13. In Fig. 2a, however, the circuit board 3 provides a surface 3' for mounting both the waveguide antenna 2 and the chip 11.

[0078] In Fig. 2a, the waveguide antenna 2 can also comprise several waveguide channels 5 that can be arranged through layers 7 and 8 to form air-filled channels with a zigzag shape. The waveguide channels 5 can also have metallized walls 5' and comprise at least a portion of the air-filled channel that forms a certain angle, preferably a perpendicular angle, with layers 7 and 8 of the waveguide antenna 2. This transverse portion 5' of the waveguide channels 5 can have at least one inlet 5'' facing the surface 3' of the printed circuit board 3. Furthermore, the waveguide antenna 2 is also attached to the surface 3' of the printed circuit board 3 via at least one laser solder joint 4. The laser solder joints 4 are also arranged between the waveguide antenna 2 and the surface 3' of the printed circuit board 3 such that they are located directly next to the R. 413958

[0079] - 14 -

[0080] The input 5'' of the waveguide channels 5 is located. The laser solder joints 4 define the distance between the surface 3' of the circuit board 3 and the waveguide antenna 2. In other embodiments, in addition to the laser solder joints 4, further laser solder joints or laser solder balls (not shown here) can be arranged between the waveguide antenna 2 and the surface 3' of the circuit board 3 in the outer areas to ensure a firm mechanical connection and a corresponding distance between the waveguide antenna 2 and the circuit board 3. In the outer areas between the waveguide antenna 2 and the surface 3' of the circuit board 3, spacers can also be attached to the waveguide antenna (not shown here) to adjust the distance between the waveguide antenna 2 and the circuit board 3 in the outer areas.

[0081] In contrast to Fig. 1, the chip 11 can be arranged between the waveguide channels 5 of the waveguide antenna 2, so that the waveguide antenna 2 can have a hollow shape that adequately accommodates the chip 11. The chip 11 can be connected to the surface 3' of the printed circuit board 3 via a ball grid array (BGA) 19. Thermally and electrically conductive material 20 can cover the surface 3' below the chip 11. In another embodiment, the thermally conductive material 20 does not cover the surface of the printed circuit board 3 above the chip 11 in order not to interfere with the connection between the chip 11 and the printed circuit board 3.

[0082] In Fig. 2a, the transition between the chip 11 and the waveguide antenna 2 can be made via at least one high-frequency line 16 (which is not visible in the cross-sectional example of the radar sensor 1 in Fig. 2a). The high-frequency line 16 can, for example, be a microstrip line 16. Fig. 2b shows a top view of the high-frequency line 16, which can be arranged as a thin metallic conductor strip on the surface 3' of the circuit board 3. The high-frequency line 16 can extend from the chip 11 (not shown here) to an air-filled waveguide channel 5 of a waveguide antenna 2 and run under or partially through the waveguide antenna 2. The high-frequency line 16 can be connected to the chip 11 by a soldering method or an R. 413958

[0083] - 15 - other connection methods. For example, the high-frequency line 16 can be connected at one end to the chip 11 via at least one soldered sphere of the sphere grid arrangement 19. The high-frequency line 16 should be correctly aligned with the soldered spheres to avoid mismatches and minimize parasitic effects. At the other end, the high-frequency line 16 terminates in a radiating element 17 located in the air-filled space of a waveguide channel 5. At least one radiating element 17 connected to a high-frequency line 16 can be arranged in each waveguide channel 5 of the waveguide antenna 2. A radiating element is a small interface at the end of a high-frequency line that can provide a means of coupling the electromagnetic waves generated by a chip into a waveguide antenna.The radiating element 17 can have a square shape, but also other configurations such as a rectangular, circular, E- or U-shape. Both the radiating element 17 and the high-frequency line 16 can be etched or printed elements on the surface 3' of the circuit board 3.

[0084] The width and thickness of the high-frequency line 16 and the radiating element 17 are carefully designed according to the desired requirements. Furthermore, it is desirable that the thickness of the high-frequency line 16 be at most equal to, and preferably less than, the thickness of the laser solder joints 4 that connect the waveguide antenna 2 to the surface 3' of the circuit board 3. In this way, the high-frequency line 16 can run beneath the waveguide antenna 2. In other embodiments, the waveguide antennas 2 could have at least one hollow form that could accommodate the high-frequency line 16 from the chip 11 to the waveguide channel 5, provided that the thickness between the surface 3' and the waveguide antenna 2, defined by the thickness of the laser solder joints 4, is less than that of the high-frequency line 16.The high-frequency line 16 should maintain a specific distance from the metallized walls of the waveguide antenna, regardless of whether the high-frequency line 16 runs below the waveguide antenna or follows a hollow shape within the antenna. The distance should typically not be R. 413958.

[0085] - 16 - less than 0.5 mm to reduce unwanted interactions between the microfeed line and the waveguide antenna structure.

[0086] Furthermore, in Fig. 2b, the laser solder joints 4 continuously surround the entrance 5"' of the waveguide channels 5, except for the area where the high-frequency line 16 projects into the waveguide channel 5. In this area, the laser solder joints 4 are interrupted. Despite this interruption, the laser solder joints 4 provide an overall strong connection between the waveguide antenna and the printed circuit board 3, optimizing signal transmission and reception. The laser solder joints 4 can be limited in the transverse direction of the printed circuit board 3, so that the laser solder joints 4 form soldered narrow strips that preferably extend within 1 mm or less from the walls 5" of the waveguide channels 5'. These soldered narrow strips are preferably arranged between a solderable surface of the waveguide antenna 2 and a solderable surface 18 of the printed circuit board 3.

[0087] Figures 3a and 3b show a manufacturing method for a radar sensor 1 in which a waveguide antenna 2 is connected to a printed circuit board 3 by laser soldering according to a further embodiment of the present invention. A chip 11, comprising a launcher 12, is mounted on a surface 3" of a printed circuit board 3 using a standard soldering method, preferably using an arrangement of solder balls on the underside of the printed circuit board 3 to connect the chip 11 to the printed circuit board 3 on a side opposite the waveguide antenna 2. In a second embodiment, a chip 11 can be mounted on a surface 3' of a printed circuit board 3 using a standard soldering method, preferably using an arrangement of solder balls on the underside of the printed circuit board 3 to connect the chip 11 to the printed circuit board 3 on the same side as the waveguide antenna 2.

[0088] The waveguide antenna 2 is then mechanically and conductively connected to the surface 3' of the circuit board 3 using a laser soldering process. One for the R. 413958

[0089] - 17 -

[0090] A solder paste 10 suitable for laser soldering is applied to a solderable surface 18 of the printed circuit board 3. The solder paste 10 may contain at least one solder alloy, which forms the main part of the laser solder joints, and a flux specially formulated for the rapid heating process.

[0091] Solder paste 10 is applied continuously directly adjacent to the edges 6' of at least one plated via 6 of the printed circuit board 3, in a manner different from the application of solder balls. In the second embodiment, the solder paste 10 could be applied to a smooth surface 3' of the printed circuit board 3, such that after the waveguide antenna 2 is mounted on the printed circuit board 3, the solder paste 10 is located directly adjacent to the input 5"' of the waveguide channels 5 of the waveguide antenna 2. In such an embodiment, a high-frequency line 16 can be arranged on the printed circuit board 3 before the radar sensor is mounted. The high-frequency line 16 extends from the chip 11 to at least one waveguide channel 5 of the waveguide antenna 2. The solder paste 10 is then applied continuously to the surface 3', except in the area where the high-frequency line 16 extends into the waveguide channels 5.The solder paste 10 is applied as a narrow strip, so that the laser solder joints 4 have a width of 1 mm or ideally even narrower.

[0092] The waveguide antenna 1 is then suitably mounted onto the surface 3' of the circuit board 3, such that the solder paste 10 is in contact with a solderable surface of the waveguide antenna 2, while the waveguide channels 5 of the waveguide antenna 2 are correctly aligned with the corresponding plated vias 6 of the circuit board 3. In the second embodiment, where the chip

[0093] Since the waveguide antenna 2 and the waveguide antenna 2 are mounted on the same surface 3' of the circuit board 3, the solder paste 10 is located only directly next to the input 5"' of the waveguide channels 5 of the waveguide antenna 2.

[0094] The solder paste 10 is then selectively heated with at least one focused laser beam 14, such that the laser beam does not touch the waveguide antenna 2 and the circuit board 3. In Fig. 3a, the laser beam 14 is applied to two solder paste deposits 10 located on both sides of the input 5"' of the R. 413958

[0095] - 18 -

[0096] waveguide channel 5 and the edges of the plated vias 6 are located. In the second embodiment, in which the chip 11 is mounted on the same surface 3' of the circuit board 3, two solder paste deposits 10, which are located on both sides of the inputs 5"' of the waveguide channels 5, can also be heated with a laser beam 14 with a similar beam direction.

[0097] The laser beam 14 is guided through the space between the surface 3' of the circuit board 3 and the waveguide antenna 2, initially heating the central solder paste deposit 10. Here, the beam is oriented perpendicular to the length of the circuit board 3, but in other configurations, the laser beam could be oriented differently. After the solder paste deposit 10 has cooled, the laser solder joints 4 are formed as narrow strips directly adjacent to the entrance 5'' of the waveguide channels 5. In both configurations, the laser solder joints 4 provide a strong connection between the waveguide antenna 2 and the circuit board 3, simultaneously optimizing the reception and transmission of high-frequency signals. In Figures 3a and 3b, the waveguide antenna 2 already consists of several layers 7, 8 that are connected to each other before the waveguide antenna 2 is mounted on the circuit board 3. In other configurations, the mounting sequence can be changed.

[0098] Figures 4a and 4b show a manufacturing process for a radar sensor 1, in which the waveguide antenna 2 is connected to a printed circuit board 3 by laser soldering according to a further embodiment of the present invention. In Figure 4a, the connection of a waveguide antenna 2 to a printed circuit board 3 is carried out by laser soldering before several layers 7 and 8 of a waveguide antenna 2 are connected to each other.

[0099] A chip 11 containing a launcher 12 is attached to a surface 3" of a printed circuit board 3 using a standard soldering method, preferably using an arrangement of solder balls on the underside of the printed circuit board 3 to connect the chip 11 to the printed circuit board 3 on a side opposite the waveguide antenna 2. In a second embodiment, a chip 11 can be attached to a surface 3' of a printed circuit board 3 using an R. 413958

[0100] - 19 -

[0101] The chip 11 is mounted using a standard soldering process, preferably using an arrangement of solder balls on the underside of the circuit board 3 to connect the chip 11 to the circuit board 3 on the same side as the waveguide antenna 2.

[0102] The waveguide antenna 2 is then mechanically and conductively connected to the surface 3' of the printed circuit board 3 using a laser soldering process. A solder paste 10 suitable for the laser soldering process is applied to a solderable surface 18 of the surface 3' of the printed circuit board 3. The solder paste 10 can contain at least one solder alloy, which forms the main part of the laser solder joints, and a flux specially formulated for the rapid heating process. The solder paste 10 is applied directly adjacent to the edges 6' of at least one plated via 6 of the printed circuit board 3 in a continuous manner, which differs from the application of solder balls. In the second embodiment, the solder paste 10 could be applied to a smooth surface 3' of the printed circuit board 3, so that after the waveguide antenna 2 is mounted on the printed circuit board 3, the solder paste 10 is located directly adjacent to the entrance 5'' of the waveguide channels 5 of the waveguide antenna 2.In this configuration, a high-frequency line 16 can be arranged on the circuit board 3 before the radar sensor is mounted. The high-frequency line 16 extends from the chip 11 to at least one waveguide channel 5 of the waveguide antenna 2. The solder paste 10 is then continuously applied to the surface 3', except in the area where the high-frequency line 16 extends into the waveguide channels 5. The solder paste 10 is applied as a narrow strip, so that the laser solder joints 4 are 1 mm wide or ideally even narrower.

[0103] Layer 7 of the waveguide antenna 2 is then suitably mounted on the surface 3' of the circuit board 3, such that the solder paste 10 is in contact with a solderable surface of layer 7 of the waveguide antenna 2, while at least one waveguide channel 5 of the waveguide antenna 2 is correctly aligned with a corresponding plated via 6 of the circuit board 3. In the second embodiment, in which the chip 11 and the waveguide antenna 2 are mounted on the circuit board 3, R. 413958

[0104] - 20 - mounted on the same surface 3' of the circuit board 3, the solder paste 10 is located directly next to the inlet 5"' of the waveguide channels 5 of the waveguide antenna 2. The solder paste 10 is then selectively heated with at least one focused laser beam 14, such that the laser beam does not touch the layer 7 of the waveguide antenna 2 or the circuit board 3. The laser beam 14 is applied to at least two solder paste deposits 10 located on both sides of the inlet 5"' of the waveguide channel 5 and the edges of the plated vias 6. In the second embodiment, where the chip 11 is mounted on the same surface 3' of the circuit board 3, at least two solder paste deposits 10 located on both sides of the inlet 5"' of a waveguide channel 5 can also be heated with a laser beam 14 with a similar beam direction.

[0105] The laser beam 14 is guided through the air-filled waveguide channels 5 to heat the multiple solder paste deposits 10. Specifically, the laser beam 14 is guided through a portion 5' of the air-filled channel that forms a specific angle, more precisely a perpendicular angle, with the layer 7 of the waveguide antenna 2. In other embodiments, the laser beam could be oriented differently. For example, at the interface between the waveguide antenna 2 and the circuit board 3, the laser beam could be oriented perpendicular to the length of the circuit board 3. After the solder paste deposit 10 has cooled, laser solder joints 4 are formed as narrow strips in the immediate vicinity of the entrance 5''' of the waveguide channels 5. In both embodiments, the laser solder joints 4 provide a solid connection between the waveguide antenna 2 and the circuit board 3 and optimize the reception and transmission of high-frequency signals.

[0106] Layer 7 can then be joined to layer 8 using laser soldering. In other embodiments, layer 7 can be joined to layer 8 using conventional soldering methods, e.g., with tin-bismuth solder. However, such a joining process is carried out at relatively high temperatures, which requires a thermoplastic material that can withstand high temperatures. R. 413958

[0107] - 21 -

[0108] Fig. 5 shows a manufacturing process for a radar sensor 1 in which the waveguide antenna 2 is connected to a printed circuit board 3 by laser soldering, according to a further embodiment of the present invention. In Fig. 5, the connection of the waveguide antenna 2 to the printed circuit board 3 is carried out by laser soldering before a chip 11 is mounted on a surface 3" of the printed circuit board 3. The step of connecting the waveguide antenna 2 to the printed circuit board 3 by laser soldering is similar to that described in Figs. 3 and 4 for a radar sensor configuration in which the printed circuit board 3 has at least one via 6. In Fig. 5, however, the laser beam 14 can heat several solder paste deposits 10 through the vias 6, which are located directly next to the edges 6' of the vias 6. After cooling, the solder paste deposits 10 then form continuous laser solder joints 4 as narrow strips.The chip 11 can then be mounted on a surface 3' of the circuit board 3 using standard soldering methods, preferably using an arrangement of solder balls on the underside of the circuit board 3 to connect the chip 11 to the circuit board 3 on a opposite side of the waveguide antenna 2.

[0109] Fig. 6 shows various assembly arrangements for manufacturing a radar sensor 1 according to different embodiments of the present invention. In step SO, a waveguide antenna 2, a printed circuit board 3, and a chip 11 are provided. In step S1c, the chip 11 is mounted on the printed circuit board 3, as described in Figs. 3 and 4. In a radar sensor embodiment in which a chip 11 is contained in a hollow form of a waveguide antenna 2 between at least two waveguide channels 5, the chip 11 should be mounted before connecting the waveguide antenna 2 to the printed circuit board 3 (S1c). In step S1ax, several layers 7 and 8 of the waveguide antenna 2 are connected to each other, as described in Fig. 4. These assembly steps can be carried out before or after steps S2a-S2d of connecting the waveguide antenna 2 to the printed circuit board 3 by means of laser soldering.Furthermore, process step S1c can be performed before or after process step S1Ax. In step 2a, the solder paste 10 for laser soldering is applied as a narrow strip to a surface 3' of the printed circuit board 3R. 413958.

[0110] - 22 - applied, as described in Figures 3 and 4. In step 2b, the waveguide antenna 2 is arranged on the circuit board 3 in a suitable manner, as described in Figures 3 and 4. In step 2c, a laser beam 14 heats the multiple solder paste deposits 10. In step 2d, after cooling, the solder paste deposits form laser solder joints 4 as narrow strips, which establish a strong mechanical and conductive connection between the waveguide antenna 2 and the circuit board 3. Steps S3c and S3Ax correspond to the same steps as S1c and S1Ax, namely the mounting of a chip 11 on a circuit board 3 and the bonding of several layers 7, 8 of a waveguide antenna 2.

[0111] However, steps S3c and S3Ax are performed after steps S2a-S2d, which involve connecting the waveguide antenna 2 to the circuit board 3 by laser soldering. Assembly step S3c can be performed before or after assembly step S3Ax. In the final step S4, the

[0112] The waveguide antenna 2, the circuit board 3 and the chip 11 are assembled with other components in a housing 13 of a radar sensor 1.

Claims

R. 413958 - 23 - Claims 1. Radar sensor (1) comprising a waveguide antenna (2), a circuit board (3), and a chip (11), characterized in that the waveguide antenna (2) and the circuit board (3) are mechanically and conductively connected to each other by at least one laser solder connection (4).

2. Radar sensor (1) according to claim 1, wherein the circuit board (3) excludes at least one through-hole or taboo zone, both configured to connect the circuit board (3) to the waveguide antenna (2) with a connecting means comprising at least one screw or clip, and wherein the waveguide antenna (2) excludes at least one screw zone or sleeve, both configured to connect the waveguide antenna (2) to the circuit board (3).

3. Radar sensor (1) according to claim 1 or 2, wherein the waveguide antenna (2) has at least one waveguide channel (5) with at least one metallized wall (5') and the at least one laser solder joint (4) is located in close proximity to the at least one wall (5') of the waveguide channel (5) to form a continuous smooth wall.

4. Radar sensor (1) according to claim 3, wherein the at least one laser solder joint (4) is a narrow strip which is preferably located within 1 mm or less of the at least one wall (5') of the waveguide channel (5) extends.

5. Radar sensor (1) according to one of claims 1 to 4, wherein at least one means (15, 6) for transmitting and receiving microwave signals from the chip (11) to the waveguide antenna (2) comprises at least one or more plated vias (6) which are arranged in the printed circuit board (3), or a high-frequency line (16) with a radiating element (17) arranged on the circuit board (3). R. 413958 - 24 - 6. Radar sensor (1) according to claim 5, wherein additional compensation structures configured for transmitting and receiving microwave signals are excluded; wherein the additional compensation structures comprise at least one electromagnetic bandgap structure.

7. Radar sensor (1) according to claim 5 or 6, wherein the waveguide antenna (2) is mounted on one side (3') of the circuit board (3) and the chip (11) is mounted on an opposite side (3”) of the circuit board (3), and wherein the at least one means (15, 6) for transmitting and receiving the microwave signals from the chip (11) to the waveguide antenna (2) comprises the or more plated vias (6) which are directly connected to the at least one waveguide channel (5) via the laser solder connection (4) to form a continuous electrical connection.

8. Radar sensor (1) according to claim 5 or 6, wherein the waveguide antenna (2) and the chip (11) are mounted on the same side (3') of the circuit board (3), and wherein the at least one means (15) for transmitting and receiving the microwave signals from the chip (11) to the waveguide antenna (2) comprises at least one high-frequency line (16) with a radiating element (17) which is arranged on the circuit board (3).

9. Radar sensor (1) according to one of claims 1 to 8, wherein the laser solder joint (4) comprises at least a thermally and electrically conductive material.

10. Radar sensor (1) according to any one of claims 1 to 9, wherein the waveguide antenna (2) comprises at least a standard plastic or a thermoplastic material.

11. Method for manufacturing a radar sensor (1) according to any one of claims 1 to 10, characterized by the following steps: - Provide a waveguide antenna (2); R. 413958 - 25 - - Provide a printed circuit board (3); - Provide a chip (11); - Assembling the chip (11) with the circuit board (3); - mechanical and conductive connection of the waveguide antenna (2) to the circuit board (3) by at least one laser solder connection (4).

12. Method according to claim 11 for manufacturing a radar sensor (1) according to any one of claims 1 to 10, wherein the mechanical and conductive connection of the waveguide antenna (2) to the circuit board (3) is characterized by the following steps: - Applying solder paste (10) to the circuit board (3), - Mounting the waveguide antenna (2) on the circuit board (3) such that at least one waveguide channel (5) of the waveguide antenna (2) is arranged in the immediate vicinity of the soldering paste (10), - selective heating of the solder paste (10) using at least one focused laser beam (14) designed so that it does not touch the waveguide antenna (2) and the circuit board (3) and, - Forming at least one laser solder joint (4) during the cooling of the solder paste (10), which is arranged in the immediate vicinity of the at least one waveguide channel (5) of the waveguide antenna (2).

13. Method according to claim 11 or 12 for manufacturing a radar sensor according to one of claims 1 to 10, wherein the mechanical and conductive connection of the waveguide antenna (2) to the circuit board (3) takes place before or after a connection between at least one layer (7) of the waveguide antenna (2) with one or more other layers (8) of the waveguide antenna (2), wherein the connection between the layers (7, 8) of the waveguide antenna is made by soldering, preferably by laser soldering.

14. Method according to any one of claims 11 to 13 for manufacturing a radar sensor according to any one of claims 1 to 10, wherein the joining of the chip (11) with the circuit board (3) takes place before or after the mechanical and conductive connection of the waveguide antenna (2) with the circuit board (3). R. 413958 - 26 - 15. Method according to any one of claims 11 to 14 for manufacturing a radar sensor according to any one of claims 1 to 10, wherein the laser solder joint (4) between the circuit board (3) and the waveguide antenna (2) by emitting the focused laser beam (14) through the at least one waveguide channel (5) or through at least one or more plated vias of the printed circuit board (3) or across between the printed circuit board (3) and the waveguide antenna (2).

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