Circuit board, radio frequency device, radar and electronic equipment

Abstract

The embodiment of the utility model relates to the technical field of electronic devices, and provides a circuit board, a radio frequency device, a radar and electronic equipment, so as to reduce the large-angle side lobe of an antenna, improve the directivity of the antenna, prolong the operating distance of the antenna, and improve the anti-interference capability of the antenna. By adopting the circuit board, the transmission path of the signal of which the frequency is within the preset frequency band in the signal radiated to the circuit board can be changed, so that the EMC performance can be improved. The circuit board comprises a substrate which comprises a first side and a second side which are oppositely arranged; the first side of the substrate is provided with a frequency selection structure; and the frequency selection structure is used for selecting a signal of which the frequency is within a preset frequency band from the signals received from the first side of the substrate to pass through.

Description

Technical Field

[0001] This application relates to the field of electronic device technology, and in particular to a circuit board, radio frequency device, radar, and electronic equipment. Background Technology

[0002] Typically, integrated circuit chips are further integrated onto a PCB board using solder balls or other soldering components. Existing solutions use metal shielding to improve the EMC (Electromagnetic Compatibility) performance of integrated circuit chips. However, even with this solution, some signals radiated from the integrated circuit chip onto the PCB board can still cause electromagnetic interference to other devices on the PCB. Utility Model Content

[0003] This application provides a circuit board, a radio frequency device, a radar, and an electronic device. Using this circuit board can change the transmission path of signals with frequencies within a preset frequency band radiated to the circuit board, thereby improving EMC performance.

[0004] According to some embodiments of this application, a first aspect of this application provides a circuit board, including: a substrate, the substrate including a first side and a second side disposed opposite to each other; the first side of the substrate is provided with a frequency selection structure;

[0005] The frequency selection structure is used to: select signals with frequencies within a preset frequency band from the signals received from the first side of the substrate, while filtering out signals with frequencies outside the preset frequency band.

[0006] According to some embodiments of this application, a second aspect of this application provides a radio frequency device, including: a chip package and the aforementioned circuit board;

[0007] The chip package includes a packaging substrate and a chip disposed on the packaging substrate, wherein the packaging substrate integrates an antenna;

[0008] The frequency selection structure of the circuit board is positioned opposite to the chip, and a gap is provided between the frequency selection structure and the chip.

[0009] According to some embodiments of this application, a third aspect of this application provides a radar including the radio frequency device described above.

[0010] According to some embodiments of this application, a fourth aspect of this application provides an electronic device including the radar described above.

[0011] This application provides a circuit board, a radio frequency device, a radar, and an electronic device. By setting a frequency selection structure, the circuit board can select signals with frequencies within a preset frequency band from the signals received from the first side of the substrate, while filtering out signals with frequencies outside the preset frequency band. This changes the transmission path of signals with frequencies within the preset frequency band, causing these signals to be transmitted to the second side of the substrate. This is very beneficial for subsequent elimination of these signals, thereby improving EMC performance. Attached Figure Description

[0012] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A schematic diagram of the structure of a radio frequency device provided for related technologies;

[0014] Figure 2 This is a schematic diagram of the structure of a radio frequency device provided in an embodiment of this application;

[0015] Figure 3 for Figure 2 The schematic diagram of the signal transmission path of the structure shown.

[0016] Figure 4 A top view of a circuit board provided in an embodiment of this application;

[0017] Figure 5 A top view of another circuit board provided in an embodiment of this application;

[0018] Figures 6 to 17 Top views of various cutout sections provided in embodiments of this application;

[0019] Figure 18 A diagram illustrating the magnetic permeability characteristics of a ferrite material microwave absorber provided in an embodiment of this application.

[0020] Figure 19 This is a schematic diagram of the structure of a conductive part provided in an embodiment of this application;

[0021] Figure 20 This is a schematic diagram of another conductive part provided in an embodiment of this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] In the description of the embodiments of this application, "at least one" means one or more, and "multiple" means two or more, unless otherwise explicitly specified.

[0024] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0025] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0028] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0029] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. The formation or provision of a second component above or on a first component, or on the surface of a first component, or on one side of a first component, may include embodiments where the first and second components are in direct contact, and may also include embodiments where an additional component may be present between the first and second components, thereby preventing direct contact between the first and second components. For simplicity and clarity, various components may be drawn at different scales. In the drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, the formation or provision of a second component on the surface of a first component refers to direct contact between the first and second components. The term "component" may refer to: layer, film, region, portion, structure, etc.

[0030] AiP (Antenna in Package) is an advanced technology that integrates antennas and circuitry into a single package. (Reference) Figure 1 As shown, the AiP package structure 1 is mounted on the PCB (Printed Circuit Board) 3 via solder balls 2. The transmission path of the electromagnetic waves generated by the chip unit 4 of the AiP package structure 1 is as follows: Figure 1 The dashed line with arrows shows that the radiation first reaches PCB3, then is scattered by PCB3, and finally radiates outward through the gap between solder balls 2, thus significantly reducing EMC (Electromagnetic Compatibility) performance. The method of using a metal shield to improve EMC performance is not suitable for AIP package structures.

[0031] Based on this, embodiments of this application provide a circuit board, with reference to... Figure 2 As shown, it includes: a substrate 100, which includes a first side and a second side disposed opposite to each other; a frequency selection structure 101 is provided on the first side of the substrate 100; the frequency selection structure 101 is used to: select signals with frequencies within a preset frequency band from the signals received from the first side of the substrate, while filtering out signals with frequencies outside the preset frequency band.

[0032] The frequency selection structure in this application is not limited to a frequency selective surface (FSS) structure, but may also include other structures with frequency selection functionality. A frequency selective surface structure is an array structure with periodically perforated holes in a substrate, which can select signals with frequencies within a preset frequency band (e.g., Figure 3 The signal with frequency f2 shown is allowed to pass through, while signals with frequencies outside the preset frequency band (e.g., f2) are filtered out. Figure 3 The signal shown (at frequency f1) is equivalent to a bandpass filter. The principle behind this structure can be found in related technologies and will not be elaborated here. By changing the dimensions of the frequency-selective surface structure, the allowed frequency band of the signal can be altered.

[0033] The preset frequency band can be determined based on actual conditions. For example, in a radio frequency device formed by a chip package and the circuit board, if the VCO (Voltage Controlled Oscillator) of the chip circuit in the chip package generates a noise signal with a frequency of 7.2 GHz and / or 19 GHz, then the preset frequency band can include [7.2 GHz - A, 7.2 GHz + A], and / or [19 GHz - A, 19 GHz + A], where A is the difference between the noise signal's frequency and the upper (or lower) frequency limit. That is, the preset frequency band can be the frequency band of the noise signal generated by the chip package.

[0034] It should be noted that in actual radio frequency devices, the chip package may generate high-frequency noise signals above 1 GHz or low-frequency noise signals below 1 GHz (e.g., 10 MHz - 1 GHz). Since low-frequency noise signals have longer wavelengths, they are not easily radiated to the outside through the gaps between solder balls. Therefore, the frequency selection structure of this application embodiment can be used to filter out low-frequency noise signals and select only high-frequency noise signals to pass through.

[0035] The size, dimensions, and shape of the frequency selection structure in the embodiments of this application are not limited and can be selected according to actual requirements.

[0036] The circuit board provided in this application embodiment, by setting a frequency selection structure, can select signals with frequencies within a preset frequency band from the signals received from the first side of the substrate, while filtering out signals with frequencies outside the preset frequency band. This changes the transmission path of signals with frequencies within the preset frequency band, causing these signals to be transmitted to the second side of the substrate. This is very beneficial for eliminating these signals and thus improving EMC performance.

[0037] In one or more embodiments, reference is made to Figure 4 and Figure 5 As shown, the frequency selection structure 101 includes a substrate 1011, which has multiple hollowed-out portions 1012 arranged in an array. The substrate can be made of a metallic conductive material, such as copper, aluminum, silver, platinum, or gold.

[0038] There are no restrictions on the number, size, shape, or dimensions of the cutouts.

[0039] In some implementations, the size L of the cutout portion satisfies: L=c×n / (4×f), where c is the speed of light, n is a positive integer, and f is the frequency within a preset frequency band.

[0040] The dimensions of the cutout section need to be determined based on the actual shape of the cutout section.

[0041] For ease of implementation, the orthographic projection of the boundary of the hollowed-out portion onto the first reference plane can be as follows: Figures 6 to 10 The centrally symmetric figure shown; or, it could be as follows: Figures 11 to 16 The axisymmetric figure shown has its first reference plane parallel to the base; of course, it can also be other types, such as... Figure 17 The irregular shapes shown are not limited here.

[0042] Figures 6 to 11 The dimension L of the hollowed-out portion 1012 shown is the perimeter of the corresponding shape, with... Figure 6 Let's take an example to illustrate. Figure 6The dimension L of the cutout shown refers to the sum of the side lengths of all sides A1 to A8 of the cutout. Figure 12 , Figure 13 , Figure 16 and Figure 17 The dimension L of the cutout shown is the longest side length; both types of cutouts have a single dimension, allowing signals of one frequency band to pass through. Figure 14 and Figure 15 The dimensions of the cutout shown include the minimum side length L1 and the maximum side length L2. Since the lengths of L1 and L2 are different, this type of cutout allows signals from two frequency bands to pass through.

[0043] In one or more embodiments, reference is made to Figure 2 As shown, a frequency selection structure 101 is embedded on the surface of the first side of the substrate 100, and the frequency selection structure 101 and the substrate 100 are an integral structure; or, a frequency selection structure is provided on the surface of the first side of the substrate.

[0044] To prevent signals passing through the frequency selection structure from propagating outwards from inside the circuit board, reference Figure 2 As shown, the substrate 100 is also provided with a plurality of metal flow guides 102; Reference Figure 4 and Figure 5 As shown, a plurality of metal flow guides 102 are arranged around the frequency selection structure 101 and extend from the first side of the substrate 100 to the second side of the substrate.

[0045] The method of forming the metal flow guide is not limited. For example, multiple through holes can be formed at predetermined positions, extending from the first side of the substrate to the second side. Then, the through holes are filled with a metal material, such as copper, aluminum, silver, platinum, or gold, to form the metal flow guide. For example, the cross-section of the through holes can be circular, rectangular, hexagonal, etc.

[0046] By setting multiple metal flow guides, all signals passing through the frequency selection structure are guided to the second side of the substrate, thereby facilitating complete signal cancellation and further improving EMC performance.

[0047] The arrangement of multiple metal flow guides is not limited; however, to improve and ensure the flow guiding effect, refer to... Figure 5 As shown, multiple metal flow guides 102 are arranged in concentric rings. The spacing d between adjacent rings must be less than 1 / 40th of the wavelength of the signal passing through the frequency selection structure to achieve the flow guiding effect. For example, if the frequency of the signal passing through the frequency selection structure is 7.2 GHz, then the spacing between adjacent rings is 1 mm. In some embodiments, the spacing between adjacent rings ranges from [1 mm to 2 mm]. The spacing between adjacent rings can be 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, or 2 mm, which ensures the flow guiding effect while facilitating manufacturing.

[0048] In this embodiment, the number of concentric rings is not limited. For example, the number of concentric rings can be 2, 3, 4, or 5 rings. Considering reducing costs while ensuring the flow guiding effect, the number of concentric rings can be selected as 2. The metal flow guiding parts of adjacent rings can be staggered or aligned; this is not limited here. To further improve the flow guiding effect, the metal flow guiding parts of adjacent rings can be staggered.

[0049] To completely eliminate signals through the frequency-selective structure and improve EMC performance, refer to... Figure 2 As shown, the circuit board also includes an absorbing section 103, which absorbs signals passing through the frequency selection structure 101. The absorbing section 103 is disposed on the second side of the substrate 100. The orthographic projections of the metal current guide section 102 and the frequency selection structure 101 on the second reference surface are located within the orthographic projection of the absorbing section 103 on the second reference surface, and the second reference surface is parallel to the substrate. In this way, in the RF device formed by fixing the chip package with solder balls and the circuit board, EMC performance can be improved without modifying the chip package or reducing the signal strength of the chip.

[0050] It should be noted that the material of the absorbing part can be determined according to the frequency of the signal passing through the frequency selective structure, so as to ensure that the absorbing part can completely absorb the signal passing through the frequency selective structure.

[0051] In some embodiments, the thickness of the absorbing portion ranges from [0.1 mm to 2 mm], and the absorbing portion can be a non-metallic magnetic absorbing sheet. A non-metallic magnetic absorbing sheet can absorb electromagnetic waves within a certain frequency range. The specific material of the non-metallic magnetic absorbing sheet is not limited here; for example, the non-metallic magnetic absorbing sheet may include a ferrite material absorbing sheet. (See reference...) Figure 18 As shown, the larger the imaginary part μ” of the permeability of the ferrite material, the higher the corresponding frequency attenuation rate and the better the absorption effect. This material has a good attenuation effect for signals above 100MHz. By adjusting the material and material type of the absorbing sheet, so that the peak value of the imaginary part of the permeability of the absorbing sheet material covers the frequency point to be absorbed, the absorption of electromagnetic waves in the corresponding frequency range can be achieved.

[0052] In some implementations, in order to simultaneously dissipate heat and absorb electromagnetic waves, the material of the absorbing part can be a mixture of heat dissipation material and electromagnetic wave absorbing material (e.g., non-metallic magnetic material).

[0053] It should be noted that the circuit board provided in the embodiments of this application can be as follows: Figure 2As shown, multiple metal flow guides 102, frequency selection structures 101, and wave-absorbing sections 103 are simultaneously provided; or, the circuit board provided in this application embodiment may also have multiple metal flow guides 102 and frequency selection structures 101 simultaneously, without wave-absorbing sections 103; or, the circuit board provided in this application embodiment may also have frequency selection structures 101, without multiple metal flow guides 102 and wave-absorbing sections 103; this application embodiment does not limit this, and can choose according to the actual situation.

[0054] This application also provides a radio frequency device, referenced in the embodiments. Figure 2 As shown, the package includes: a chip package 20 and any of the aforementioned circuit boards 10; the chip package 20 includes a packaging substrate 200 and a chip disposed on the packaging substrate 200, and the packaging substrate 200 integrates an antenna 203; the frequency selection structure 101 of the circuit board 10 is disposed opposite to the chip, and a gap is provided between the frequency selection structure 101 and the chip. The chip includes a chip substrate 201 and a chip circuit 202 disposed on the substrate 201. The chip is fixed to the packaging substrate in a flip-chip manner. To facilitate electrical connection between the chip and the circuit board, the chip package 20 may also include substrate traces 204.

[0055] In this embodiment, the antenna in the chip package can receive or radiate radio frequency signals. These radio frequency signals can be FMCW (Frequency-Modulated Continuous Wave) millimeter-wave signals or radio frequency signals in other bands. Where conditions permit, they can also be applied to fields such as 5G communication. Alternatively, they can be frequency sweep signals with frequencies in the range of 100M-1GHz used for long-range detection, or frequency sweep signals with frequencies in the range of 1GHz-4GHz used for short-range detection.

[0056] In this RF device, the circuit board, by setting a frequency selection structure, can select signals with frequencies within a preset frequency band from the signals received from the first side of the substrate, while filtering out signals with frequencies outside the preset frequency band. This alters the transmission path of signals within the preset frequency band, causing these signals to be transmitted to the second side of the substrate. This is highly effective in eliminating these signals and thus improving EMC performance. This RF device achieves improved EMC performance without modifying the chip package or reducing the chip's signal strength.

[0057] In one or more embodiments, reference is made to Figure 2 As shown, the radio frequency device also includes multiple conductive parts 30; Reference Figure 19 and Figure 20As shown, multiple conductive portions 30 are arranged around the chip 200. These conductive portions secure the chip package and the circuit board, and also provide electrical connection. In some embodiments, the conductive portions are solder balls.

[0058] The arrangement of multiple conductive parts is not limited; for example, they can be arranged in a ball grid array (BGA). These conductive parts can form a cavity structure with a circular, triangular, quadrilateral, or irregular cross-section. The cavity structure can be a hollow structure using air as the transmission medium, or a solid structure using insulating material as the transmission medium; there are no limitations on this. The size of the cavity structure and the dielectric constant within it both affect the signal frequency transmitted by the cavity structure. Assuming other influencing factors remain constant, a smaller cavity structure corresponds to a higher signal frequency; conversely, a higher dielectric constant corresponds to a lower signal frequency. The chip design size and the dielectric constant of the transmission medium must be considered to meet the chip's cutoff frequency requirements.

[0059] This application also provides a radar, including the radio frequency device described above. The operating band of the radar is not limited; for example, it can operate in the millimeter-wave band, but other bands are also possible. The application scenario of the radar is not limited; for example, it can be used on transportation electronic equipment such as cars, bicycles, motorcycles, ships, subways, or trains to detect vehicles, pedestrians, overpasses, trees, or parking spaces. It can also be used in security equipment such as cameras, or in other fields; no further limitations are imposed here.

[0060] This application also provides an electronic device including the aforementioned radar. This electronic device can be a component or product used in fields such as smart homes, transportation, smart homes, consumer electronics, surveillance, industrial automation, in-cabin detection, and healthcare. For example, the electronic device can be intelligent transportation equipment (e.g., automobiles, bicycles, motorcycles, ships, subways, or trains), security equipment (e.g., cameras), liquid level / flow rate detection equipment, smart wearable devices (e.g., wristbands or glasses), smart home devices (e.g., robot vacuums, door locks, televisions, air conditioners, or smart lights), various communication devices (e.g., mobile phones or tablets), and devices such as barriers, intelligent traffic lights, intelligent signs, traffic cameras, or various industrial robotic arms (or robots). Alternatively, it can be various instruments for detecting vital signs or various devices equipped with such instruments, such as in-cabin vehicle detection, indoor occupant monitoring, smart medical devices, or consumer electronic devices.

[0061] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A circuit board, characterized in that, include: A substrate, the substrate including a first side and a second side disposed opposite to each other; the first side of the substrate is provided with a frequency selection structure; The frequency selection structure is used to select signals whose frequencies fall within a preset frequency band from the signals received from the first side of the substrate.

2. The circuit board according to claim 1, characterized in that, The frequency selection structure includes a substrate, which has multiple hollowed-out sections arranged in an array.

3. The circuit board according to claim 2, characterized in that, The dimension L of the hollowed-out portion satisfies: L = c × n / (4 × f), where c is the speed of light, n is a positive integer, and f is the frequency within the preset frequency band.

4. The circuit board according to claim 2, characterized in that, The boundary of the hollowed-out portion is projected onto the first reference plane as a centrally symmetric or axisymmetric figure, and the first reference plane is parallel to the substrate.

5. The circuit board according to any one of claims 1-4, characterized in that, The frequency selection structure is embedded on the surface of the first side of the substrate; or, the frequency selection structure is disposed on the surface of the first side of the substrate.

6. The circuit board according to any one of claims 1-4, characterized in that, The substrate is also provided with multiple metal flow guides; A plurality of the metal flow guides are arranged around the frequency selection structure and extend from a first side of the substrate to a second side of the substrate.

7. The circuit board according to claim 6, characterized in that, The plurality of the metal flow guides are arranged in a concentric ring.

8. The circuit board according to claim 7, characterized in that, The spacing between adjacent rings is less than 1 / 40th of the wavelength of the signal passing through the frequency selection structure.

9. The circuit board according to any one of claims 1-4, characterized in that, The circuit board also includes a wave-absorbing section, which is used to absorb signals passing through the frequency selection structure; The absorbing portion is disposed on the second side of the substrate.

10. The circuit board according to claim 9, characterized in that, The substrate is further provided with a plurality of metal flow guides; the plurality of metal flow guides are arranged around the frequency selection structure and extend from a first side of the substrate to a second side of the substrate.

11. The circuit board according to claim 10, characterized in that, The orthographic projections of the metal flow guide and the frequency selection structure on the second reference plane are located within the orthographic projection of the absorbing part on the second reference plane, and the second reference plane is parallel to the substrate.

12. The circuit board according to claim 9, characterized in that, The thickness of the absorbing part ranges from 0.1 mm to 2 mm.

13. A radio frequency device, characterized in that, include: A chip package and a circuit board as described in any one of claims 1-12; The chip package includes a packaging substrate and a chip disposed on the packaging substrate, wherein the packaging substrate integrates an antenna; The frequency selection structure of the circuit board is positioned opposite to the chip, and a gap is provided between the frequency selection structure and the chip.

14. The radio frequency device according to claim 13, characterized in that, The radio frequency device also includes a plurality of conductive parts; the plurality of conductive parts are arranged around the chip.

15. The radio frequency device according to claim 14, characterized in that, The conductive part is a solder ball.

16. A radar, characterized in that, Includes the radio frequency device as described in any one of claims 13-15.

17. An electronic device, characterized in that, Including the radar as described in claim 16.

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