Circuit board for radar sensors having a metallic fill structure, and method for producing a circuit board for radar sensors having a metallic fill structure

Abstract

A circuit board for radar sensors including a substrate having a topside and a lower surface. The circuit board has at least one antenna device, which is situated on the topside of the substrate and is developed out of a metal layer. In addition, the circuit board has a fill structure situated on the topside of the substrate, which is developed out of the metal layer. The fill structure is situated at a distance from the antenna device in a surface region of the topside of the substrate, the surface region not being taken up by the antenna device. The fill structure has no electrical connection to the antenna device. The surface utilization of the fill structure amounts to between 50% and 300% of that of a surface utilization of the antenna device.

Claims

1. A circuit board for a radar sensor, comprising: a substrate having a topside and an underside; at least one antenna device situated on the topside of the substrate and developed out of a metal layer; and a fill structure situated on the topside of the substrate, the fill structure being developed out of the metal layer, and the fill structure being situated at a distance from the antenna device in a surface region of the topside of the substrate that is not taken up by the antenna device; wherein the fill structure has no electrical connection to the antenna device, and wherein a surface utilization of the fill structure amounting to between 50% and 300% of a surface utilization of the antenna device.

2. The circuit board as recited in claim 1, wherein the surface utilization of the fill structure amounts to between 75% and 200% of that of the surface utilization of the antenna device.

3. The circuit board as recited in claim 1, wherein the surface utilization of the fill structure amounts to between 90% and 150% of that of the surface utilization of the antenna device.

4. The circuit board as recited in claim 1, wherein the surface utilization of the fill structure has 100% of the surface utilization of the antenna device.

5. The circuit board as recited in claim 1, wherein the fill structure is developed in a rectangular or square shape.

6. The circuit board as recited in claim 5, wherein the rectangular or square shape of the fill structure and the antenna device have edges, and the edges of the fill structure extend with a same orientation as the edges of the antenna device.

7. The circuit board as recited in claim 5, wherein the fill structure includes a multitude of fill structures situated in a grid with a different orientation and clearances.

8. The circuit board as recited in claim 7, wherein the clearances between the fill structures amount to between 50% and 200% of a clearance of the antenna device.

9. The circuit board as recited in claim 7, wherein the clearances between the fill structures amount to between 75% and 150% of a clearance of the antenna device.

10. The circuit board as recited in claim 7, wherein the clearances between the fill structures have a clearance of 100% of a clearance of the antenna device.

11. A method for producing a circuit board for a radar sensor including a substrate having a topside and an underside, the method comprising the following steps: applying a fully continuous metal layer on the topside of a substrate; and developing at least one antenna device situated on the topside of the substrate, and a fill structure, the antenna device and the fill structure being developed out of the metal layer, wherein the fill structure is situated at a distance from the antenna device in a surface region of the topside of the substrate that is not taken up by the antenna device; wherein the fill structure has no electrical connection to the antenna device; and wherein a surface utilization of the fill structure amounts to between 50% and 300% of that of a surface utilization of the antenna device.

12. The method as recited in claim 11, wherein the fill structure is developed in a rectangular or square shape.

13. The method as recited in claim 12, wherein the rectangular or square shape of the fill structure and the antenna device have edges, and the edges of the fill structure extend with a same orientation as the edges of the antenna device.

14. A radar sensor, comprising: a circuit board including: a substrate having a topside and an underside; at least one antenna device situated on the topside of the substrate and developed out of a metal layer; and a fill structure situated on the topside of the substrate, which is developed out of the metal layer, the fill structure being situated at a distance from the antenna device in a surface region of the topside of the substrate that is not taken up by the antenna device; wherein the fill structure has no electrical connection to the antenna device, and wherein a surface utilization of the fill structure amounting to between 50% and 300% of a surface utilization of the antenna device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic illustration of the circuit board according to a first example embodiment of the present invention.

(2) FIG. 2 shows a schematic illustration of a circuit board in a cross-sectional view without developed metal structures and fill structures.

(3) FIG. 3 shows a schematic illustration of the circuit board with fill structures placed in a grid according to a second example embodiment of the present invention.

(4) FIG. 4 shows a schematic illustration to describe a method for producing a circuit board for radar sensors having a metallic fill structure according to the first example embodiment of the present invention.

(5) FIG. 5 shows a schematic illustration of an exemplary circuit board for radar sensors.

(6) Identical or functionally equivalent elements in the figures have been provided with the same reference numerals.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(7) FIG. 1 shows a schematic illustration of circuit board 10 according to a first embodiment of the present invention.

(8) Reference numeral 10 in FIG. 1 denotes a circuit board according to the present invention. Circuit board 10 includes a substrate 1 having a topside 4 and an underside 3. At least one antenna device 11 is developed on topside 4 of substrate 1. In one embodiment, antenna device 11 has two antennas. Antenna device 11 is developed out of a metal layer 2, preferably from copper. Antenna device 11 includes the antenna, circuit trace 13, and solder surface 12. Circuit trace 13 connects the antenna to solder surface 12. By way of vias in solder surface 12, a monolithic microwave integrated circuit (MMIC) is able to be connected to the antenna by way of circuit trace 13. In one preferred embodiment, the MMIC is situated on the side of topside 4 of substrate 1 (not shown). In an alternative embodiment, the MMIC is disposed on underside 3 of substrate 1.

(9) In the embodiment of the present invention, fill structures 14 are situated on topside 4 of substrate 1. Fill structures 14 are set apart from antenna device 11 and situated in a surface region of topside 4 of substrate 1 not taken up by antenna device 11. Fill structure 14 has no electrical connection to antenna device 11. In one advantageous embodiment, the surface utilization of fill structure 14 amounts to a between 50 and 300% of a surface utilization of antenna device 11.

(10) FIG. 1 shows an embodiment of circuit board 10 of a radar sensor in which three fill structures 14 are formed. It is advantageous for an optimal production process if the circuit board surface is covered with metal as uniformly as possible. The free surfaces of circuit board 1 are therefore occupied by periodic fill structures 14 having dimensions on the order of magnitude of antenna device 11. FIG. 1 is an exemplary representation of the present invention which, however, does not restrict the present invention. It is furthermore possible that a multitude of fill structures 14 is formed on topside 4 of substrate 1.

(11) Fill structures 14 may be embodied in the shape of rectangles or squares. In an advantageous manner, fill structures 14 are able to be placed in a regular grid. The edges of rectangular or square fill structures 14 are placed with the same orientation as the edges of the antenna device. Therefore, the edges of fill structures 14 are advantageously subject to the same production tolerances as the antenna device, which improves a check of the production tolerances. In one example embodiment of the present invention, the clearances between the rectangular and square fill structures 14 are on the order of magnitude of antenna device 11.

(12) FIG. 2 is a schematic representation of a circuit board in a cross-sectional view without developed metal structures and fill structures.

(13) Reference numeral 10 in FIG. 2 denotes a circuit board according to the present invention. Circuit board 10 includes a substrate 1 having an underside 3 and a topside 4. Metal layer 2 is formed on topside 4. From metal layer 2, antenna device 11, including at least one antenna, circuit traces and solder surfaces, as well as fill structures 14 is formed out of metal layer 2. Metal layer 2 preferably includes copper.

(14) FIG. 3 is a schematic representation of the circuit board including fill structures 14 situated in the grid according to a second embodiment of the present invention.

(15) FIG. 3 shows an antenna array having two antenna devices 11. Antenna device 11 has antennas and circuit traces 13. Antenna device 11 is formed out of a metal layer 2, preferably copper. Antenna device 11 has clearances A and B. In FIG. 3, fill structures 14 having dimensions on the order of magnitude of antenna device 11 are shown. The antennas of antenna devices 11 have a clearance B with respect to each other. Individual fill structures 14 of the fill structures situated in a grid have the same clearance B relative to one another. By developing the same clearance, the etching process on the fill structures on circuit board 1 is carried out in the same way as on antenna device 11. Fill structures 14 have a rectangular or square shape. A multitude of fill structures 14 is situated in groups of fill structures 14. This offers the advantage that the surface utilization of fill structure 14 corresponds to the surface utilization of antenna device 11. If fill structures 14 are all uniformly aligned in a perpendicular fashion in the ideal case, then this results in a considerably greater surface utilization for fill structures 14 than for antenna device 11. The alternating horizontal and vertical placement of fill structures 14 in a grid produces a balanced surface ratio. In an advantageous manner, the entire production process including the etching and copper application is therefore improved. In addition, the regular placement of fill structures 14 in a grid makes it possible for an optical system to check the grid including the periodic placement of the fill structures.

(16) FIG. 4 shows a schematic representation in order to describe a method for producing a circuit board for radar sensors having a metallic fill structure according to the first embodiment of the present invention.

(17) In a first step S1, a fully continuous metal layer 2 is applied to a topside 4 of substrate 1. Metallic layer 2 is preferably made of copper. In a further step S2, at least one antenna device 11 and a fill structure 14 are developed on the topside of substrate 1. Antenna device 11 and fill structure 14 are developed out of metal layer 2. In addition, fill structure 14 is situated in a surface region of topside 4 of substrate 1 at a distance from antenna device 11. The surface region is an area on topside 4 of substrate 1 that is not taken up by antenna device 11. Antenna device 11 includes at least one antenna, at least one circuit trace 13, and at least one solder surface 12. The antenna of antenna device 11 and solder surface 12 are electrically connected by circuit trace 13. Solder surface 12 may have vias for the electrical connection of a monolithic microwave integrated circuit to antenna device 11. Fill structure 14 situated on topside 4 of substrate 1 has no electrical connection to antenna device 11. The surface utilization of fill structure 14 amounts to between 50% and 300% of the surface utilization of antenna device 11.

(18) The method of the present invention optimizes the production process of circuit board 1, in particular the step of etching antenna device 11 and fill structures 14 out of continuous metal layer 2. In addition, the copper application takes place more homogeneously because a greater copper share is included on circuit board 1 because of fill structures 14, and the copper distributes itself more optimally on the plurality of structures, in particular the fill structures, or grows uniformly in an epitaxial manner.