CN115707171A

CN115707171A - Circuit board, antenna structure and electronic equipment

Info

Publication number: CN115707171A
Application number: CN202110935457.1A
Authority: CN
Inventors: 罗兵; 覃雯斐
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-08-13
Filing date: 2021-08-13
Publication date: 2023-02-17
Also published as: WO2023016024A1

Abstract

The application provides a circuit board, antenna structure and electronic equipment, this circuit board includes: a dielectric substrate; the first conductive pattern layer is arranged on one side of the dielectric substrate and comprises a first signal line; the second conductive pattern layer is arranged on the other side of the dielectric substrate and comprises a second signal line and two second ground wires arranged on two sides of the second signal line at intervals; the second signal line comprises a plurality of transmission line segments which are arranged in a line, a fracture is formed between every two adjacent transmission line segments, the second conductive pattern layer further comprises a connecting bridge which is electrically isolated from the second signal line, the connecting bridge is located in the fracture and electrically connected with two second ground wires, and each transmission line segment is electrically connected with the first signal line. This application improves through the structure to coplanar waveguide on the circuit board, has guaranteed the integrality and the closure in ground level, has improved the interference killing feature of circuit board from this to the electromagnetic radiation that the circuit board produced external components and parts has been reduced.

Description

Circuit board, antenna structure and electronic equipment

Technical Field

The present application relates to the field of communications technologies, and in particular, to a circuit board, an antenna structure, and an electronic device.

Background

A circuit board is the basic carrier for electrical connections of electronic components, the main function of which is to support the electronic components and to interconnect them. In modern communication circuit designs, signal transmission between different electronic components on a circuit board is typically accomplished by transmission lines. A transmission line is a linear structure carrying electromagnetic energy and is an important component of a telecommunication system for transmitting radio frequency signals carrying information from one point to another. In electronic devices, commonly used transmission lines include microstrip lines, strip lines, single-layer coplanar waveguides, double-layer coplanar waveguides, and other structures.

The double-layer coplanar waveguide is a common transmission line structure, and compared with transmission line structures such as microstrip lines or strip lines, the double-layer coplanar waveguide can reduce the distribution of an electric field in a dielectric substrate, and further can inhibit the dielectric loss to a certain extent. However, at this time, the ground plane of the circuit board is formed by two ground wires and a signal wire of the coplanar waveguide, and the signal wire and the ground wires on both sides have a slot (gap) with a large length, so that the integrity of the ground plane of the circuit board is damaged, the sealing performance of the circuit board is poor, and the shielding performance of the circuit board on electromagnetic waves is also poor. Due to the reasons, electromagnetic elements on the circuit board are easy to generate electromagnetic wave coupling with external components, the anti-interference performance of the circuit board is poor, and radiation interference is easy to generate on the external components.

Disclosure of Invention

The application provides a circuit board, antenna structure and electronic equipment improves through the structure to coplanar waveguide on the circuit board, has reduced slotted length on the horizon, has guaranteed the integrality and the closure on horizon, has improved the interference killing feature of circuit board from this to the electromagnetic radiation that the circuit board produced external components and parts has been reduced.

In a first aspect, a circuit board is provided, which includes: a dielectric substrate made of an insulating material; the first conductive pattern layer is arranged on one side of the dielectric substrate and comprises a first signal line; the second conductive pattern layer is arranged on the other side of the dielectric substrate and comprises a second signal line and two second ground wires which are arranged on two sides of the second signal line at intervals; the second signal line comprises a plurality of transmission line segments arranged in a line, a fracture is formed between every two adjacent transmission line segments, the second conductive pattern layer further comprises a connecting bridge electrically isolated from the second signal line, the connecting bridge is located in the fracture and electrically connected with two second ground wires, and each transmission line segment is electrically connected with the first signal line.

According to the circuit board provided by the embodiment of the application, the second conductive pattern layer comprises a second signal line and two second ground lines which jointly form a coplanar waveguide transmission line structure, and the coplanar waveguide transmission line structure can form a ground plane of the circuit board. The second signal line is cut off into a plurality of transmission line sections, a fracture is arranged between every two adjacent transmission line sections, and a connecting bridge for connecting second ground wires on two sides is arranged in the fracture. This application can reduce grooved length between second signal line and the second ground wire through setting up the connecting bridge, has increased the area that sets up of conducting pattern on the medium base plate (has increased the area covered at ground level promptly), has improved the integrality and the closure at ground level, and then has improved the shielding performance to the electromagnetic wave at ground level. At the moment, under the high-efficiency isolation effect of the ground plane, the electromagnetic element on the circuit board is not easy to generate electromagnetic wave coupling with external components, so that the anti-interference performance of the circuit board is improved, and the influence of the circuit board on the electromagnetic radiation generated by the external components is reduced.

The second conductive pattern layer in the embodiment of the application can be integrated on the dielectric substrate through processes such as plane printing and the like, so that the advantages of miniaturization of the size of the traditional coplanar waveguide transmission line, easiness in integration with a chip and the like are kept. The arrangement of the connecting bridge does not need to add extra working procedures, and has the implementation cost close to zero. Due to the reasons, the circuit board provided by the embodiment of the application has the advantages of small size, high integration level, low cost and the like, and has wide application space in electronic products.

The circuit board that this application embodiment provided adopts coplanar waveguide transmission line structure to carry out radio frequency signal's transmission, compares in transmission line structures such as microstrip line or stripline, can make main electric field distribution in the air, has reduced the distribution of electric field in the dielectric substrate from this, the problem of suppression dielectric loss that can the certain extent, and then can realize radio frequency signal's low-loss transmission, has improved signal transmission's quality. In addition, because the signal electric field is mainly distributed in the air, the unit length delay is small, the phase winding can be reduced, and the low-delay transmission of the signal is realized.

Optionally, the circuit board includes, but is not limited to: the substrate comprises a bottom plate, a middle plate, a back plate, a flexible circuit board, a rigid-flex board, a terminal circuit board, a packaging carrier plate, a low-temperature co-fired ceramic substrate or a high-temperature co-fired ceramic substrate and the like. The package carrier may be a system-in-package carrier, a single chip package carrier, a multi-chip package carrier, or a ball grid array package carrier.

When the circuit board is a rigid circuit board, the dielectric substrate is made of a hard insulating material. Alternatively, the material of the dielectric substrate may be at least one of a ceramic material, a resin material, a glass material, or a hard plastic.

For example, the dielectric substrate may be made of at least one material selected from alumina ceramics, aluminum nitride ceramics, phenolic resins, epoxy resins, brominated epoxy resins, polyester, or polytetrafluoroethylene.

When the circuit board is a flexible circuit board, the dielectric substrate is made of a flexible insulating material. For example, the dielectric substrate may be made of at least one material of polyester, polyimide, fluorocarbon, aromatic polyamide, or the like. The circuit board may then be used in a foldable electronic device, such as a foldable cell phone.

In a possible design, the connecting bridge and the fracture are multiple, and each connecting bridge is located in the fracture. Through the setting, can be under the longer condition of signal transmission distance, according to more than connecting bridges of setting up of local conditions, ensure that transmission line segment can not be too long, ensure promptly that the fluting length between transmission line segment and the second ground can not too big, guaranteed the integrality and the closure in ground plane from this, ensured promptly that the ground plane can have good shielding performance. In addition, fluting length is too big to be unfavorable for production and processing (milling cutter cutting route appears the error too long easily), and this application shortens grooved length through setting up a plurality of connecting bridges 134, can improve the efficiency of production, reduction in production cost.

Alternatively, the number of interruptions can be greater than, equal to, or less than the number of connecting bridges.

Alternatively, the number of connecting bridges provided in different fractures may be the same or different.

Optionally, only one connecting bridge, or a plurality of connecting bridges, or no connecting bridge may be provided in the fracture, which is not limited in this application.

For example, the number of the fractures is greater than that of the connecting bridges, the connecting bridges are arranged in the fractures in a one-to-one correspondence manner, and the connecting bridges are not arranged in the rest fractures due to the fact that the number of the fractures is greater.

In a possible design, the number of the connecting bridges is equal to that of the fractures, and a plurality of the connecting bridges correspond to a plurality of the fractures one to one. Through the arrangement, the coverage area of the conductive pattern on the dielectric substrate can be increased as much as possible, namely the area of the ground plane is increased, and the integrity and the closure of the ground plane are ensured. In addition, the processing procedure is simplified, and the production cost is reduced.

In one possible design, the length of the transmission line segment is less than 0.5 times the wavelength of the electromagnetic wave signal transmitted by the second signal line. Through the arrangement, the transmission line segment can be prevented from resonating under the action of other electromagnetic wave signals, and the transmission stability of the second signal line can be ensured. In addition, the above setting can also be used as a reference for dividing the second signal line into how many transmission line segments.

In one possible design, each transmission line segment is electrically connected to the first signal line through a metalized via.

In one possible design, the first conductive pattern layer further includes two first ground lines disposed at both sides of the first signal line at intervals, and the second ground line is electrically connected to the first ground lines.

In a possible design, a dielectric slot is further disposed on the dielectric substrate, and the dielectric slot is located between the transmission line segment and the second ground. Through setting up the medium fluting, can dig out the partial medium that is located between transmission line segment and the second ground, make the electric field that transmission line segment produced can be more distributed in the air from this, and reduce the distribution of electric field in the medium, and then can further reduce the dielectric loss of transmission line, improve the transmission quality of signal. In a possible design, the dielectric slot is a strip-shaped slot and penetrates through both sides of the dielectric substrate (that is, the dielectric slot is a through slot), and the dielectric slot is arranged to extend along the length direction of the transmission line segment. Through the arrangement, more media can be excavated, the distribution of an electric field in the media is reduced as much as possible, the dielectric loss of the transmission line can be further reduced, and the transmission quality of signals is improved.

Optionally, in other embodiments, the dielectric slot may also be a blind slot, where the dielectric slot does not penetrate through both sides of the dielectric substrate.

In one possible embodiment, the distance between the slot edge of the dielectric slot and the transmission line section, the second ground or the connecting bridge is 0.05 to 0.3 mm.

For example, it may be 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.2 mm, or the like.

By arranging a certain safety distance between the notch and the metal pattern, the edge of the metal pattern (such as copper foil) can be prevented from being damaged by a milling cutter in the grooving process, so that metal burrs and exposed copper foil are formed, and the performances of the transmission line in the aspects of corrosion resistance, oxidation resistance and the like are influenced.

In a possible design, a first conductive sidewall is arranged on a slot wall of the medium slot on a side adjacent to the transmission line segment, and the transmission line segment is electrically connected with the first signal line through the first conductive sidewall; and a second conductive side wall is arranged on the groove wall of the medium groove adjacent to one side of the second ground wire, the second conductive side wall is electrically isolated from the first conductive side wall, and the second ground wire is electrically connected with the first ground wire through the second conductive side wall.

Through the arrangement, on one hand, the medium slotting can be made as large as possible, the edge of the slot opening of the medium slotting can be close to the edge of the metal pattern, so that the medium of the rest parts is almost completely removed except the part covered by the connecting bridge in the area between the second signal line and the second ground, and the main component of the electric field is distributed in the air, so that the transmission line loss caused by the medium can be reduced to the maximum extent.

On the other hand, the first conductive side wall is electrically connected with the signal line of the double-layer coplanar waveguide, the second conductive side wall is electrically connected with the ground line of the double-layer coplanar waveguide, and the first conductive side wall and the second conductive side wall are close to each other and are opposite to each other, so that the opposite area of the signal line and the ground line can be increased, the current distribution in the line is more uniform, the conductor loss is reduced, and the impedance of the transmission line is reduced.

In one possible design, the second ground is electrically connected to the first ground through a metalized via.

In one possible design, the circuit board is a double-sided board.

In one possible design, the circuit board is a multi-layer board having a plurality of board bodies, and the dielectric substrate is any one of the plurality of board bodies.

Alternatively, there may be only one plate body between the first conductive pattern layer and the second conductive pattern layer, in this case, the one plate body is the dielectric substrate.

Optionally, a plurality of plate bodies may be disposed between the first conductive pattern layer and the second conductive pattern layer, and in this case, the dielectric substrate is one of the plurality of plate bodies.

In one possible design, the metalized via is a through hole, a blind hole, or a buried hole.

In one possible design, the second conductive pattern layer is a metal layer made by an etching process.

In a second aspect, an antenna structure is further provided, where the antenna structure includes an antenna unit and a circuit board provided in any one of the possible designs of the first aspect, the antenna unit is disposed on one side of the circuit board, and the circuit board forms a reflector of the antenna unit.

Because the circuit board that first aspect provided has guaranteed the integrality and the closure of ground plane (or, do not destroy the integrality of ground plane), can reduce the electromagnetic radiation interference that the circuit board produced external components and parts, therefore the circuit board can be used as directional antenna's reflecting plate, and can not influence the directional diagram performance of antenna.

Alternatively, the antenna structure may be an active antenna or a passive antenna.

Alternatively, the antenna element may be a dipole antenna.

Alternatively, the antenna unit may include a plurality of antenna elements and be arranged in an array on the circuit board.

Alternatively, the antenna element is electrically connected to the circuit board, for example a transmission line structure on the circuit board may serve as a feed line for the antenna element.

In a third aspect, an electronic device is provided, which includes a housing and a circuit board provided in any one of the possible designs of the first aspect, wherein the circuit board is located in the housing.

Alternatively, the electronic device may be a handheld device, an in-vehicle device, a wearable device, a computing device, or other processing device connected to a wireless modem.

For example, the electronic device may be a mobile phone, a tablet computer, a notebook computer, a smart watch, a smart bracelet, smart glasses, or a smart television (smart screen).

Alternatively, the electronic device may be a communication device, which may be a base station or a radar, for example.

In a possible design, the electronic device further includes an antenna unit located in the housing, the antenna unit is located on one side of the circuit board, and the circuit board constitutes a reflection plate of the antenna unit.

Drawings

Fig. 1 shows a schematic of the structure of various different types of transmission lines.

Fig. 2 shows a schematic diagram of the principle that the microstrip line causes loss in the signal transmission process.

Fig. 3 is a schematic structural diagram of a suspended stripline and a suspended microstrip line.

Fig. 4 is a schematic diagram of the principle of reducing dielectric loss by coplanar waveguides.

Fig. 5 shows three common coplanar waveguide transmission line structures.

Fig. 6 is a schematic structural diagram of an antenna structure without a transmission line on a circuit board.

Fig. 7 is a radiation pattern of the antenna structure shown in fig. 6.

Fig. 8 is a schematic structural diagram of an antenna structure in which a circuit board is provided with a microstrip line.

Fig. 9 is a radiation pattern of the antenna structure shown in fig. 8.

Fig. 10 is a schematic structural diagram of an antenna structure in which a circuit board is provided with a double-layer coplanar waveguide.

Fig. 11 is a radiation pattern of the antenna structure shown in fig. 10.

Fig. 12 is a schematic structural diagram of a circuit board according to an embodiment of the present application.

Fig. 13 is an exploded view of the circuit board shown in fig. 12.

Fig. 14 is a top view and a bottom view of the circuit board shown in fig. 12.

Fig. 15 is a cross-sectional view from the AA in fig. 12.

Fig. 16 is a schematic structural diagram of another example of the circuit board according to the embodiment of the present application.

Fig. 17 is an exploded view of the circuit board shown in fig. 16.

Fig. 18 is a top view and a bottom view of the circuit board shown in fig. 16.

Fig. 19 is a sectional view of still another example of a circuit board according to an embodiment of the present application.

Fig. 20 is an exploded view of the circuit board shown in fig. 19.

Fig. 21 is a schematic structural diagram of another example of a circuit board according to an embodiment of the present application.

Fig. 22 is an exploded view of the circuit board shown in fig. 21.

Fig. 23 is a top view and a bottom view of the circuit board shown in fig. 21.

Fig. 24 is a cross-sectional view from the BB view in fig. 21.

Fig. 25 is a schematic structural diagram of another example of the circuit board according to the embodiment of the present application.

Fig. 26 is an exploded view of the circuit board shown in fig. 25.

Fig. 27 is a top view and a bottom view of the circuit board shown in fig. 25.

Fig. 28 is a cross-sectional view taken from the perspective CC of fig. 25.

Fig. 29 is a flow chart illustrating the process of forming the metalized sidewall.

Fig. 30 is a schematic structural diagram of an antenna structure provided in the present application.

Fig. 31 is a radiation pattern of an antenna structure provided in an embodiment of the present application.

Reference numerals are as follows:

11. a dielectric substrate; 12. a signal line; 13. a ground plane; 14. a ground wire; 15. metallizing the via hole;

21. a dielectric substrate; 22. a reference ground plane; 23. a microstrip line; 2H, magnetic field; 2E, an electric field;

31. a metal plate; 32. a metal sidewall; 33. a cavity; 34. a metal signal line; 35. a gap;

41. a dielectric substrate; 42. a signal line; 43. a ground line; 44. a ground plane; 45. metallizing the via hole; 4E, an electric field;

51. a dielectric substrate; 52. a dipole antenna; 53. a microstrip line; 54. a coplanar waveguide; 55. metallizing the via hole;

100. a circuit board; 110. a dielectric substrate; 120. a first conductive pattern layer; 121. a first signal line; 122. a first ground line; 130. a second conductive pattern layer; 131. a second signal line; 131a, a transmission line segment; 132. a second ground line; 133. breaking off; 134. a connecting bridge; 140. metallizing the via hole; 150. slotting a medium; 151. a first conductive sidewall; 152. a second conductive sidewall; 160. a third conductive pattern layer; 170. a fourth conductive pattern layer.

Detailed Description

Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it is to be understood that the terms "first", "second", and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, features defined as "first," "second," etc. may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In the description of the present application, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted" and "connected" are to be interpreted broadly, e.g., as being either a fixed connection, a removable connection, or an integral connection; may be mechanically, electrically or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as the case may be.

In the description of the present application, it is to be understood that the terms "upper", "lower", "side", "front", "rear", "inner", "outer", and the like indicate orientations or positional relationships based on installation, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present application.

It should be noted that the same reference numerals are used to denote the same components or parts in the embodiments of the present application, and for the same parts in the embodiments of the present application, only one of the parts or parts may be given the reference numeral, and it should be understood that the reference numerals are also applicable to the other same parts or parts.

A circuit board is the basic carrier for electrical connections of electronic components, the main function of which is to support the electronic components and to interconnect them. The circuit board enables the circuit to be miniaturized and visualized, and plays an important role in batch production and optimized layout of the circuit. Circuit boards are generally divided by the number of circuit layers, and include single-sided boards, double-sided boards, and multilayer boards.

The single-sided board is the most basic circuit board, the components are concentrated on one surface of the dielectric substrate, and the wires are concentrated on the other surface of the dielectric substrate. The double-sided board is a circuit board in which wiring (copper plating) is performed on both sides of a dielectric substrate. At this time, the conductive lines on both sides of the dielectric substrate constitute conductive pattern layers, and the dielectric substrate constitutes an insulating layer interposed between the two conductive pattern layers. The multilayer circuit board comprises a plurality of conductive pattern layers (more than 3 layers and 3 layers) and a plurality of insulating layers (namely a plurality of dielectric substrates), two adjacent conductive pattern layers are separated by the insulating layers, and the two adjacent conductive pattern layers are electrically connected through conductive through holes (also called metallized through holes).

In modern communication circuit designs, signal transmission between different electronic components on a circuit board is usually realized by transmission lines (transmission lines). A transmission line is a linear structure for the transmission of electromagnetic energy, which is an important component of telecommunication systems, for the transmission of electromagnetic waves (radio frequency signals) carrying information from one point to another along a route defined by the transmission line. In electronic devices, commonly used transmission lines include microstrip lines (microstrip), strip lines (strip lines), coplanar waveguides (CPW), grounded coplanar waveguides (GCPW), substrate Integrated Waveguides (SIW), coaxial cables, waveguides, twisted pairs, and the like.

Fig. 1 shows a schematic of the structure of various different types of transmission lines. As shown in fig. 1 (a), the microstrip line is a strip-shaped signal line 12 formed on the top surface of a dielectric substrate 11, the signal line 12 is made of a metal material (e.g., copper) and can be used for propagating a radio frequency signal, the dielectric substrate 11 is made of an insulating medium and can function as an electrical insulator, and a ground plane 13 is provided on the bottom surface of the dielectric substrate 11. The ground plane, also referred to herein as a reference ground, a reference ground plane or ground plane, etc., is typically a plated-on copper foil (copper sheet).

As shown in part (c) of fig. 1, the strip line is a strip signal line 12 between the bonding surfaces of the two dielectric substrates 11, the surfaces of the two dielectric substrates 11 that are away from each other are respectively provided with a ground plane 13, so that the signal line 12 is between the two ground planes 13, the dielectric substrate 11 is provided with a metalized via 15, the two ground planes 13 on the two sides are electrically connected through the metalized via 15, and the potentials of the two ground planes 13 can be ensured to be equal. The dielectric substrate 11 is provided with a through hole communicating with the two sides, and a metal conductive material is disposed in the through hole to form the metalized via 15, and two ends of the metal conductive material are electrically connected to the ground planes 13 on the two sides, respectively.

As shown in part (d) of fig. 1, the coplanar waveguide, also called a coplanar microstrip transmission line, includes 3 strip conductors formed on the top surface of the dielectric substrate 11, the 3 strip conductors being parallel to each other and spaced apart from each other. The strip conductor in the middle constitutes a signal line 12 for transmitting signals, and the two strip conductors on both sides constitute two ground lines 14. The ground line 14 may be designed to be as wide as practical so that the two ground lines 14 and the signal line 12 together form a "ground plane" with a trench (a gap between the signal line 12 and the ground line 14). The ground plane may act as a reflective surface for the antenna.

As shown in part (b) of fig. 1, the grounded coplanar waveguide is also called a back-metallized coplanar waveguide, and on the basis of the coplanar waveguide shown in part (d) of fig. 1, a ground plane 13 is further provided on the ground plane of the dielectric substrate 11, and the ground plane 13 is electrically connected to the ground line 14 on the other side through a metallized via 15. Compared with the coplanar waveguide shown in part (d) of fig. 1, the arrangement of the ground plane 13 not only enhances the mechanical strength of the dielectric substrate 11, but also provides a good heat dissipation medium for the active device.

As shown in parts (a) - (d) of fig. 1, in the above transmission line structure, several types of transmission lines, such as microstrip line, stripline, GCPW, and CPW, have the characteristics of compact structure and high integration, and are convenient to be manufactured by using a planar printing process, and thus are generally applied to planar circuits, such as Printed Circuit Boards (PCBs), chips, and package substrates. Such transmission lines are easy to integrate with the circuit, but are generally lossy. In fig. 1, the parts (e), (f), and (g) are respectively the structural schematic diagrams of the waveguide, the twisted pair, and the coaxial cable. Transmission line structures such as waveguides, twisted pairs and coaxial cables are generally applied to signal connection between devices or modules, and such transmission lines have small loss but are large in size and inconvenient to integrate with circuits.

Although some transmission lines, such as microstrip lines, strip lines, GCPW, and CPW, have the advantages of small size, high integration level, and convenience for integration with chips or circuits, there is a great disadvantage that the loss is large, and especially in the case of transmitting high-frequency signals, the loss becomes a key problem that restricts the application of such transmission lines.

The main reason for the loss is that the conductors of these transmission line structures are printed and attached on the dielectric substrate, and during the signal transmission process, most of the electric field is distributed in the dielectric substrate, and since the molecules of the insulating medium constituting the dielectric substrate will vibrate under the action of the alternating electric field, and convert part of the electromagnetic energy into heat energy, the signal energy at the output point of the transmission line is reduced, and the dielectric loss (i.e. the loss caused by the insulating medium of the dielectric substrate) is formed.

The dielectric loss will be described with reference to a specific example. Fig. 2 shows a schematic diagram of the principle that the microstrip line causes loss in the signal transmission process. As shown in fig. 2, the dielectric substrate 21 is provided with a microstrip line 23 on the top surface and a reference ground plane 22 on the bottom surface. In a state that the microstrip line 23 is electrically operated, for example, when a high-frequency signal is transmitted, an electric field 2E (a solid arrow portion in fig. 2) and a magnetic field 2H (a dashed line portion in fig. 2) are formed on the periphery of the microstrip line 23, as can be seen from fig. 2, the direction of the electric field 2E is directed from the microstrip line 23 to the reference ground plane 22 on the other side through the middle dielectric substrate 21, so that most of the electric field 2E is distributed in the dielectric substrate 21, and dielectric molecules constituting the dielectric substrate 21 vibrate under the action of the alternating electric field to convert part of electromagnetic energy into heat energy, thereby reducing signal energy at an output point of the microstrip line 23 and forming dielectric loss.

The losses caused by the medium are on the one hand related to the properties of the material, determined by the microscopic molecular structure of the material; on the other hand, in relation to the frequency of the transmitted signal, the higher the frequency, the greater the losses. Currently, the dielectric loss is generally reduced from three aspects of improving the material characteristics of the dielectric substrate, reducing the distribution of the electric field in the dielectric substrate, and adopting the coplanar waveguide structure. These three modes are described below.

1. Dielectric loss is reduced by improving the material properties of the dielectric substrate.

In order to reduce the dielectric loss, the first method that can be used is to improve the characteristics of the material constituting the dielectric substrate, and many manufacturers on the market currently push out a series of PCB board products for high-frequency signal applications, which achieve the reduction of the dielectric loss by changing the microscopic molecular structure of the material.

However, such materials generally suffer from 3 problems: (1) the material cost is high, and a large amount of manpower and material resources are required to be invested for researching and developing novel materials. (2) The deterioration of other properties besides dielectric loss, leading to increased cost of application, such as deterioration of temperature stability, flame retardancy, corrosion resistance, etc. of the material. (3) The loss performance is still difficult to meet the requirement of a circuit system, and although the formulation improvement of the material can reduce the dielectric loss to a large extent, the dielectric loss cannot be reduced infinitely to the extent of approaching the air. The above reasons make it less feasible to reduce the dielectric loss by improving the properties of the material.

2. Dielectric loss is reduced by reducing the distribution of the electric field in the dielectric substrate.

Another method for reducing the dielectric loss is to reduce the distribution of the electric field in the medium as much as possible, in which a suspended line structure is used, including a suspended stripline and a suspended microstrip, and the basic structure is shown in fig. 3. Fig. 3 is a schematic structural diagram of a suspended stripline and a suspended microstrip line, in which part (a) in fig. 3 shows a basic structure of the suspended stripline, and part (b) in fig. 3 shows a basic structure of the suspended microstrip line.

As shown in part (a) of fig. 3, the suspended stripline structure includes two metal plates 31 arranged at an interval, and two metal sidewalls 32 arranged between the two metal plates 31 and at an interval, the two metal plates 31 and the two metal sidewalls 32 together enclose a cavity 33, and a metal signal line 34 is suspended in the cavity 33. As shown in part (b) of fig. 3, the suspended microstrip line structure includes a metal plate 31, a metal signal line 34 suspended above the metal plate 31 with a gap 35 between the metal plate 31 and the metal signal line 34. The metal signal lines 34 are suspended, so that the metal signal lines 34 and the dielectric substrate can be separated from each other (an air layer is formed in the middle), and the metal signal lines 34 and the dielectric substrate have a certain distance, so that an electric field formed by the metal signal lines 34 is mostly distributed in the air, and the distribution of the electric field in the medium is reduced as much as possible.

Although the suspended line structure achieves the purpose of reducing the dielectric loss, the signal line is separated from the ground plane and is not printed and attached to the same dielectric substrate, so that the structural complexity is increased, an additional reflecting plate and a supporting component are required to be added, the integration level is greatly reduced, and the cost is greatly increased. For example, the prior art with patent publication No. CN106785284A discloses a suspended stripline structure formed by stacking multiple layers of PCBs, and the structure realizes the suspension of striplines through 5 layers of PCBs, and the cost is raised by more than 5 times and the thickness is increased by more than 2 times compared with the common double-sided PCB.

In contrast, the suspended microstrip line shown in part (a) of fig. 3 has a simpler structure, but a complicated supporting structure is also required to suspend the signal conductor, and meanwhile, in order to reduce the manufacturing difficulty and reduce the influence of the assembly error on the impedance of the suspended microstrip line, the metal signal line 34 and the metal plate 31 are generally arranged at a longer distance, which also causes the suspended microstrip line to have poor sealing performance, and is easy to have problems of external radiation (forming external interference and increasing loss), coupling between adjacent lines, and the like.

3. Dielectric loss is reduced by employing a coplanar waveguide structure.

Another transmission line structure that reduces the electric field distribution in a dielectric substrate is a coplanar waveguide. Fig. 4 is a schematic diagram of the principle of reducing dielectric loss by coplanar waveguides. As shown in fig. 4, one surface of the dielectric substrate 41 is provided with a coplanar waveguide by printing or the like, the coplanar waveguide includes a signal line 42 and two ground lines 43 juxtaposed on opposite sides of the signal line 42, and the ground lines 43 and the signal line 42 are spaced apart from each other.

In a state where the signal line 42 is electrically operated, an electric field 4E (solid arrow portion in fig. 4) is formed on the peripheral side of the signal line 42. As can be seen from fig. 2, the direction of the electric field 4E is from the signal line 42 to the ground line 43 through the gap (slot) formed between the signal line 42 and the ground line 43, rather than perpendicular to the dielectric substrate 41, so that a part of the electric field 4E is located in the dielectric substrate 41 and another part is distributed in the air, thereby reducing the distribution of the electric field 4E in the dielectric substrate 41, suppressing the vibration of the dielectric molecules, and reducing the dielectric loss.

Fig. 5 shows three common coplanar waveguide transmission line structures. In fig. 5, (a) is a cross-sectional view of a single-layer coplanar waveguide transmission line structure. Part (b) of fig. 5 is a cross-sectional view of a single-layer coplanar waveguide transmission line structure with a reference ground. Part (c) of fig. 5 is a cross-sectional view of a two-layer coplanar waveguide transmission line structure.

As shown in part (a) of fig. 5, reducing the dielectric loss by using a single-layer coplanar waveguide is one of the most common ways. However, although the single-layer coplanar waveguide reduces the distribution of the electric field in the medium to a certain extent, the transmission line impedance is high due to the small facing area between the signal line 42 and the ground line 43, and the current distribution is concentrated at the edge of the microstrip line due to the skin effect, and the conductor loss is increased due to the small current distribution area, so that the single-layer coplanar waveguide is not used in practical electronic products.

As shown in part (b) of fig. 5, for a single-layer coplanar waveguide transmission line structure with reference to ground, coplanar waveguides and ground planes 44 are disposed on two opposite sides of the dielectric substrate 41, so that the structure is similar to a microstrip line, and the electric field is still largely distributed in the dielectric, which has no effect on improving the loss, and the effect is to enhance the isolation between the microstrip line and other adjacent transmission lines.

As shown in part (c) of fig. 5, for the double-layer coplanar waveguide transmission line structure, two coplanar waveguides are respectively disposed on two opposite sides of the dielectric substrate 41, and electrical connection between the signal lines 42 on both sides and between the ground lines 43 on both sides is achieved through a plurality of metallized vias 45.

Generally, a complete ground plane is required in the design of a circuit board of a high-frequency electronic product, otherwise, the problems of reduction of the anti-interference performance of the circuit board, increase of external interference radiation and the like can be caused. The double-layer coplanar waveguide transmission line structure is not used in practical electronic products, and has the problems that the ground plane of the circuit board is formed by two ground wires 43 of the coplanar waveguide and a signal wire 42 together, and a slot with a large length is arranged between the signal wire 42 and the ground wires 43 at two sides, so that the integrity of the ground plane of the circuit board is damaged, the sealing performance of the circuit board is poor, and the shielding performance of electromagnetic waves is also poor. Electromagnetic waves generated by electromagnetic elements such as coplanar waveguides on the circuit board are easy to emit to the outside of the circuit board through the slots to cause electromagnetic interference on other components, and the electromagnetic waves generated by other components are easy to influence the electromagnetic elements on the circuit board through the slots. The above-mentioned problems of the double-layer coplanar waveguide transmission line structure will be further illustrated by a specific simulation example.

Fig. 6 is a schematic structural diagram of an antenna structure without a transmission line on a circuit board. Fig. 7 is a radiation pattern of the antenna structure shown in fig. 6. As shown in the simulation scenario of fig. 6, the antenna structure includes a 180 × 180mm circuit board, on which a dipole antenna 52 with an operating frequency of 1.7GHz to 2.7GHz is disposed, the circuit board constitutes a reflection plate of the dipole antenna 52, the circuit board includes a dielectric substrate 51, a bottom surface (i.e., a surface facing away from the dipole antenna 52) of the dielectric substrate 51 is covered with a copper foil, the copper foil on the circuit board serves as a reflection surface of the dipole antenna 52, and together with the dipole antenna 52, the antenna with a directional radiation function is formed, and a radiation pattern of the antenna is shown in fig. 7.

Fig. 8 is a structural diagram of an antenna structure with a microstrip line disposed on a circuit board. Fig. 9 is a radiation pattern of the antenna structure shown in fig. 8. As shown in fig. 8, based on the scenario shown in fig. 6, as another simulation example, a microstrip line 53 with a length of 150mm is disposed on the front surface of the dielectric substrate 51 (i.e., the surface facing the dipole antenna 52), and the radiation pattern of the antenna structure is shown in fig. 9. As can be seen from comparing fig. 7 and fig. 9, the addition of the microstrip line 52 does not cause the antenna pattern to deteriorate because the copper foil on the back surface of the dielectric substrate 51 is not damaged and the reflection surface of the dipole antenna 53 remains intact.

Fig. 10 is a schematic structural diagram of an antenna structure in which a circuit board is provided with a double-layer coplanar waveguide. Fig. 11 is a radiation pattern of the antenna structure shown in fig. 10. As shown in fig. 10, on the basis of the scenario shown in fig. 6, as a further simulation example, one coplanar waveguide 54 is disposed on each of both side surfaces of the dielectric substrate 51, and the electrical connection between the signal lines on both sides and the electrical connection between the ground lines on both sides are realized by a plurality of metalized vias 55. The length of coplanar waveguide 54 is 150mm and the antenna pattern is shown in figure 11. As can be seen from a comparison between fig. 7 and fig. 11, the radiation pattern of the antenna structure is very severely deteriorated, because the introduction of the double-layer coplanar waveguide trace causes a slot with a large length to be formed on the ground plane (a slot is formed between the signal line and the ground lines on both sides), thereby destroying the integrity of the ground plane, and causing the circuit board to generate strong radiation interference to the dipole antenna 52.

In summary, compared with transmission line structures such as microstrip lines or strip lines, the double-layer coplanar waveguide can reduce the distribution of an electric field in the dielectric substrate, and further can suppress the dielectric loss to a certain extent. However, at this time, the ground plane of the circuit board is formed by two ground wires and a signal wire of the coplanar waveguide, and the signal wire and the ground wires on both sides of the signal wire are provided with a slot with a large length, so that the integrity of the ground plane of the circuit board is damaged, the closure of the circuit board is poor, and the shielding performance of the circuit board on electromagnetic waves is poor.

At the moment, electromagnetic waves generated by the electromagnetic elements such as the coplanar waveguide and the like on the circuit board are easy to shoot to the outside of the circuit board through the slot to cause interference to other components, and the electromagnetic waves generated by other components are also easy to influence the electromagnetic elements on the circuit board through the slot. That is to say, the electromagnetic element on the circuit board and the external component are easily coupled by the current double-layer coplanar waveguide transmission line structure, which causes poor anti-interference performance of the circuit board itself and easily generates radiation interference to the external component.

In view of this, the embodiment of the present application provides a circuit board, an antenna structure, and an electronic device, in which a coplanar waveguide structure on the circuit board is improved, so that the length of a slot on a ground plane is reduced, and the integrity and the closure of the ground plane are improved, thereby improving the anti-interference performance of the circuit board, and reducing electromagnetic radiation generated by the circuit board to external components.

In a first aspect, an embodiment of the present application first provides a circuit board 100. Fig. 12 is a schematic structural diagram of a circuit board 100 according to an embodiment of the present application. Fig. 13 is an exploded view of the circuit board 100 shown in fig. 12. Fig. 14 is a top view and a bottom view of the circuit board 100 shown in fig. 12. Fig. 15 is a cross-sectional view from the AA in fig. 12. As shown in fig. 12 to 15, a circuit board 100 provided by the embodiment of the present application includes a dielectric substrate 110, a first conductive pattern layer 120, and a second conductive pattern layer 130.

The dielectric substrate 110 is made of an insulating material and is located between the first conductive pattern layer 120 and the second conductive pattern layer 130 to electrically isolate the two conductive layers. The first conductive pattern layer 120 is disposed on one side of the dielectric substrate 110 in a patterned manner, and the first conductive pattern layer 120 includes a first signal line 121. The first signal line 121 is used to transmit radio frequency signals, and the first signal line 121 may be a metal strip (stripe) line having a certain width.

The second conductive pattern layer 130 is disposed on the other side of the dielectric substrate 110 in a patterned manner, and the second conductive pattern layer 130 includes a second signal line 131 and two second ground lines 132 disposed at two sides of the second signal line 131 at intervals. The second signal line 131 and the two second ground lines 132, which are juxtaposed and spaced apart, together form a coplanar waveguide transmission line structure. The second signal line 131 and the two second ground lines 132 are metal strip lines each having a certain width.

Part (a) in fig. 14 is a top view of the circuit board 100, and part (b) in fig. 14 is a bottom view of the circuit board 100. As shown in fig. 13 and fig. 14 (b), the second signal line 131 includes a plurality of transmission line segments 131a (e.g., two transmission line segments in the figure) arranged in a line, and a fracture (gap) 133 is provided between two adjacent transmission line segments 131a. In other words, the discontinuity 133 divides the second signal line 131 into a plurality of transmission line segments 131a. The second conductive pattern layer 130 further includes a connection bridge 134 electrically isolated from the second signal line 131, the connection bridge 134 being located within the discontinuity 133 and electrically connecting the two second ground lines 132. That is, the breaking opening 133 is provided to allow the connection bridge 134 to pass therethrough, and the width of the breaking opening 133 is greater than that of the connection bridge 134, so that the connection bridge 134 can be electrically isolated from the two transmission line segments 131a on both sides of the breaking opening 133.

Further, as shown in fig. 13 and 15, a metalized via 140 is further disposed on the dielectric substrate 110, and the metalized via 140 is formed by opening a through hole on the dielectric substrate 110 to connect two sides and disposing a metal conductive material in the through hole (for example, on a hole wall). Each of the plurality of transmission line segments 131a is electrically connected to the first signal line 121 on the other side of the dielectric substrate 110 through at least one metalized via 140, and the first signal line 121 transmits the radio frequency signal to each of the transmission line segments 131a through the metalized via 140.

According to the circuit board 100 provided in the embodiment of the present application, the second conductive pattern layer 130 includes the second signal line 131 and the two second ground lines 132 that together constitute a coplanar waveguide transmission line structure capable of constituting a ground plane of the circuit board 100. The second signal line 131 is divided into a plurality of transmission line segments 131a, a break 133 is provided between each two adjacent transmission line segments 131a, and a connection bridge 134 connecting the second ground lines 132 on both sides is provided in the break 133. This application can reduce the length of fluting between second signal line 131 and the second ground wire 132 through setting up connecting bridge 134, has increased the area that sets up of conductive pattern on dielectric substrate 110 (has increased the area covered at ground level promptly), has improved the integrality and the closure at ground level, and then has improved the shielding performance of ground level to the electromagnetic wave. At the moment, under the high-efficiency isolation effect of the ground plane, the electromagnetic element on the circuit board is not easy to generate electromagnetic wave coupling with external components, so that the anti-interference performance of the circuit board is improved, and the influence of the circuit board on the electromagnetic radiation generated by the external components is reduced.

The second conductive pattern layer 130 in the embodiment of the present application may be integrated on the dielectric substrate 110 through a process such as planar printing, which maintains the advantages of miniaturization of the conventional coplanar waveguide transmission line, easy integration with a chip, and the like. The installation of the connecting bridge 134 does not require additional process steps, and has an implementation cost close to zero. Due to the reasons, the circuit board 100 provided by the embodiment of the application has the advantages of small size, high integration level, low cost and the like, and has a wide application space in electronic products.

The circuit board 100 provided in the embodiment of the present application uses the coplanar waveguide transmission line structure to transmit the radio frequency signal, and compared with transmission line structures such as microstrip lines or strip lines, the circuit board can distribute a main electric field in the air, thereby reducing the distribution of the electric field in the dielectric substrate 110, and suppressing the dielectric loss to a certain extent, so as to implement low-loss transmission of the radio frequency signal, and improve the quality of signal transmission. In addition, because the signal electric field is mainly distributed in the air, the unit length delay is small, the phase winding can be reduced, and the low-delay transmission of signals is realized.

The circuit board 100 provided in the embodiments of the present application is further described below with reference to the drawings. The circuit board 100 provided by the embodiment of the present application can be used for transmitting high-speed signals, and the circuit board 100 includes but is not limited to: a bottom plate, a middle plate, a back plate, a flexible printed circuit board (FPC), a rigid circuit board, a rigid-flex board, a terminal circuit board, a package carrier, a low-temperature co-fired ceramic (LTCC) substrate or a high-temperature co-fired ceramic (HTCC) substrate, etc. The package carrier may be a System In Package (SIP) carrier, a Single Chip Package (SCP) carrier, a multi-chip package (MCP) carrier, a Ball Grid Array (BGA) package carrier, or the like.

When the circuit board 100 is a rigid circuit board, the dielectric substrate 110 is made of a hard insulating material. Alternatively, the material of the dielectric substrate 110 may be at least one of a ceramic material, a resin material, a glass material, or a hard plastic.

For example, the dielectric substrate 110 may be made of at least one material selected from alumina ceramics, aluminum nitride ceramics, phenolic resins, epoxy resins, brominated epoxy resins, polyester, or polytetrafluoroethylene.

When the circuit board 100 is a flexible circuit board, the dielectric substrate 110 is composed of a flexible insulating material. For example, the dielectric substrate 110 may be made of at least one material of polyester, polyimide, fluorocarbon, or aromatic polyamide. The circuit board 100 may then be used in a foldable electronic device, such as a foldable cell phone.

Alternatively, the circuit board 100 may be a double-sided board or a multi-layer board, which is not limited in this application. In the embodiment of the present application, as shown in fig. 12 to fig. 15, the circuit board 100 is a double-sided board, in which case the circuit board 100 only includes one board body, i.e., the dielectric substrate 110, and in which the first conductive pattern layer 120 and the second conductive pattern layer 130 are respectively disposed on two opposite sides of the dielectric substrate 110.

Alternatively, in other embodiments, the circuit board 100 may also be a multi-layer board, in which case the circuit board 100 includes a plurality of board bodies stacked on each other, a conductive layer is disposed between adjacent board bodies, and the dielectric substrate 110 is any one of the plurality of board bodies. At this time, the first conductive pattern layer 120 and the second conductive pattern layer 130 are disposed on two opposite sides of the dielectric substrate 110, may be directly disposed on the dielectric substrate 110, or may be connected to the dielectric substrate 110 through an intermediate medium (e.g., at least one plate and/or a conductive layer).

As shown in fig. 12 to 15, the top surface (upper surface) of the dielectric substrate 110 is provided with a first conductive pattern layer 120, and the bottom surface (lower surface) of the dielectric substrate 110 is provided with a second conductive pattern layer 130. The two conductive pattern layers may be formed on the surface of the dielectric substrate 110 by printing, etching, or other processes. For example, a thin metal layer may be disposed on the surface of the dielectric substrate 110 by a plating process, and then, an etching process may be performed to remove excess metal on the surface of the dielectric substrate 110 for patterning, thereby forming the first conductive pattern layer 120 or the second conductive pattern layer 130.

Alternatively, the metal thin layer may be a copper foil, an aluminum foil, a beryllium copper alloy foil, or the like. That is, at this time, the first conductive pattern layer 120 and the second conductive pattern layer 130 are metal layers, and the first signal line 121, the second signal line 131, the second ground line 132, and the like are all metal strip lines.

As shown in fig. 13, part (a) of fig. 14 and fig. 15, the first conductive pattern layer 120 further includes two first ground lines 122 disposed at both sides of the first signal line 121 at intervals, and at this time, the first signal line 121 and the two first ground lines 122 together form another planar waveguide transmission line structure on the circuit board 100, that is, the circuit board 100 has a double-layered coplanar waveguide transmission line structure. The two second ground lines 132 are each electrically connected to the first ground line 122 on the corresponding side through the metalized via 140.

As shown in fig. 13 and 15, a plurality of metalized vias 140 are disposed on the dielectric substrate 110, and the metalized vias 140 are electrically connected to the ground lines or the signal lines on both sides.

Specifically, the first signal line 121 and the second signal line 131 are disposed opposite to each other, projections of the first signal line and the second signal line on the dielectric substrate 110 at least partially overlap each other, the metalized via 140 is perpendicular to the surface of the dielectric substrate 110, and a part of the metalized via 140 is located in an area where the projections overlap each other, so that the first signal line 121 and the second signal line 131 on both sides can be electrically connected.

Further, since the second signal line 131 includes a plurality of transmission line segments 131a spaced apart from each other, each of the transmission line segments 131a is electrically connected to the first signal line 121 through at least one metalized via 140.

The first ground line 122 and the second ground line 132 are oppositely arranged, projections of the first ground line 122 and the second ground line 132 are at least partially overlapped, and a part of the metalized via hole 140 is located in an area where the projections are overlapped, so that the first ground line 122 and the second ground line 132 at two sides can be electrically connected, and the electric potentials of the first ground line 122 and the second ground line 132 are ensured to be equal.

The cross-sectional shapes and sizes of the metalized vias 140 may be the same or different, and the cross-sectional shapes of the metalized vias 140 are not limited, and may be circular, square, or strip, for example.

Alternatively, in other embodiments, the electrical connection between the ground lines or the signal lines on both sides of the dielectric substrate 110 may be implemented in other manners, which is not limited in this application. For example, the other means may be a metallized slotted structure as described below.

As shown in fig. 13 and part (b) of fig. 14, the second conductive pattern layer 130 includes two transmission line segments 131a, the two transmission line segments 131a are separated from each other by a break 133, a connection bridge 134 is disposed in the break 133, and the connection bridge 134 electrically connects two second ground lines 132 on both sides of the second signal line 131.

Alternatively, the width of the second ground line 132 may be greater than that of the second signal line 131, for example, the second ground line 132 may extend to edge positions on both sides of the dielectric substrate 110, and by the above arrangement, the area of the ground plane can be increased as much as possible, so as to improve the shielding effect.

Fig. 16 is a schematic structural diagram of another example of the circuit board 100 according to the embodiment of the present application. Fig. 17 is an exploded view of the circuit board shown in fig. 16. Fig. 18 is a top view and a bottom view of the circuit board 100 shown in fig. 16. Here, part (a) in fig. 18 is a top view of the circuit board 100, and part (b) in fig. 18 is a bottom view of the circuit board 100.

As shown in fig. 16 to 18, when the distance of signal transmission is long, the second signal line 131 may be divided into more transmission line segments 131a, and there are more discontinuities 133, so that more connection bridges 134 can be provided.

Specifically, a plurality of connecting bridges 134 and fractures 133 may be provided, and each connecting bridge 134 is located in a fracture 133. Through the above arrangement, under the condition that the signal transmission distance is long, more connection bridges 134 are arranged according to local conditions, so that the transmission line segment 131a is ensured not to be too long, namely, the slotting length between the transmission line segment 131a and the second ground 132 is ensured not to be too large, the integrity and the closure of the ground plane are ensured, and the ground plane can have good shielding performance. In addition, fluting length is too big to be unfavorable for production and processing (the error appears too long in milling cutter cutting route), and this application can improve the efficiency of production, reduction in production cost through setting up a plurality of bridge 134 of connecting and shortening grooved length.

Alternatively, the number of interruptions 133 may be greater than, equal to, or less than the number of connecting bridges 134.

Alternatively, the number of connecting bridges 134 provided in different interruptions 133 may be the same or different.

Alternatively, only one connecting bridge 134, or a plurality of connecting bridges 134, or no connecting bridge 134 may be disposed in the fracture 133, which is not limited in the present application.

For example, the number of the fractures 133 is greater than the number of the connecting bridges 134, the connecting bridges 134 are disposed in the plurality of fractures 133 in a one-to-one correspondence, and the connecting bridges 134 may not be disposed in the remaining fractures 133 due to the greater number of the fractures 133.

In the embodiment of the present application, as shown in fig. 17 and fig. 18, the number of the fractures 133 is equal to the number of the connecting bridges 134, and the plurality of connecting bridges 134 are arranged in the plurality of fractures 133 in a one-to-one correspondence manner. Through the arrangement, the coverage area of the conductive pattern on the dielectric substrate 110 can be increased as much as possible, namely the area of the ground plane is increased, and the integrity and the closure of the ground plane are ensured. In addition, the processing procedure is simplified, and the production cost is reduced.

When the distance of signal transmission is long, the second signal line 131 may be divided into N +1 transmission line segments 131a by providing N discontinuities 133, where N is an integer greater than or equal to 2. For example, as shown in fig. 17 and 18, the second signal line 131 may be divided into 4 transmission line segments 131a by 3 discontinuities 133, and one connecting bridge 134 is provided in each of the 3 discontinuities 133.

Further, in the embodiment of the present application, the length of the transmission line segment 131a is less than 0.5 times the wavelength of the electromagnetic wave signal transmitted by the second signal line 131. Through the above arrangement, the transmission line segment 131a can be prevented from resonating under the action of other electromagnetic wave signals, and the stability of transmission of the second signal line 131 can be ensured. In addition, the above setting can also be used as a reference for how many transmission line segments 131a the second signal line 131 is divided into.

Fig. 19 is a sectional view of still another example of the circuit board 100 according to the embodiment of the present application. Fig. 20 is an exploded view of the circuit board 100 shown in fig. 19.

The related arrangement of the connecting bridges 134 described above is applicable not only to the double-sided boards in fig. 12 to 18, but also to multilayer boards. In the embodiment of the present application, as shown in fig. 19 and 20, the circuit board 100 is a multilayer board having a plurality of board bodies, and the dielectric substrate 110 is any one of the plurality of board bodies. The circuit board 100 may have M board bodies, and have M +1 conductive pattern layers, where M is an integer greater than or equal to 2, and adjacent two conductive pattern layers are separated by one board body. After the M board bodies are subjected to metal patterning (i.e., provided with a complete conductive pattern layer), the circuit board 100 is formed by stacking and pressing the M board bodies on each other.

Alternatively, the first conductive pattern layer 120 may be any one of the M +1 conductive pattern layers, for example, a conductive pattern layer located on the top surface or the bottom surface of the circuit board 100, or a conductive pattern layer located in the middle of two board bodies inside the circuit board 100.

Similarly, the second conductive pattern layer 130 may be any one of the M +1 conductive pattern layers, for example, a conductive pattern layer located on the top surface or the bottom surface of the circuit board 100, or a conductive pattern layer located between two board bodies inside the circuit board 100.

Alternatively, there may be only one board body between the first conductive pattern layer 120 and the second conductive pattern layer 130, in this case, the dielectric substrate 110.

Optionally, there may be a plurality of plate bodies between the first conductive pattern layer 120 and the second conductive pattern layer 130, in which case the dielectric substrate 110 is one of the plurality of plate bodies.

As shown in fig. 19 and 20, in the embodiment of the present application, the circuit board 100 has three board bodies and four conductive pattern layers, and any two adjacent conductive pattern layers are separated from each other by one board body.

Specifically, the circuit board 100 sequentially includes a first conductive pattern layer 120, a third conductive pattern layer 160, a fourth conductive pattern layer 170, and a second conductive pattern layer 130 from top to bottom, two adjacent conductive pattern layers are separated from each other by a board body, and the adjacent conductive pattern layers are electrically connected by a metalized via hole 140.

In the embodiment of the present application, the first conductive pattern layer 120 is located on the top surface of the whole circuit board 100, and the second conductive pattern layer 130 is located on the bottom surface of the whole circuit board 100, in which case the dielectric substrate 110 may be any one of three board bodies, for example, the lowest board body in the figure.

Alternatively, the third conductive pattern layer 160 may include a coplanar waveguide transmission line structure, which may be the same as the transmission line structure of the first conductive pattern layer 120 or the second conductive pattern layer 130, which is not limited in this application.

Alternatively, the fourth conductive pattern layer 170 may include a coplanar waveguide transmission line structure, which may be the same as the transmission line structure of the first conductive pattern layer 120 or the second conductive pattern layer 130, which is not limited in this application.

In summary, for the circuit board 100 having 3 or more than 3 layers of coplanar waveguide transmission line structures, the above-mentioned connection bridge 134 may be disposed on one or more layers of coplanar waveguide transmission line structures, but at least one layer of waveguide transmission line structure needs to be reserved without the connection bridge 134, so that the signal lines in the layer can be kept complete and continuous, and normal transmission of radio frequency signals is ensured.

As shown in fig. 19 and 20, the signal lines and the ground lines between the different layers may be electrically connected by the metalized vias 140. At this time, since the relative positions of the first conductive pattern layer 120 and the second conductive pattern layer 130 are not determined, that is, the position of the dielectric substrate 110 is also not determined, the metalized via 140 at least required to penetrate through the dielectric substrate 110 to connect the first conductive pattern layer 120 and the second conductive pattern layer 130 may be a through hole, a blind hole or a buried hole.

Here, the through hole, the blind hole, or the buried hole is for the entire circuit board 100, and the through hole penetrates through the bottom surface and the top surface of the entire circuit board 100. Blind vias penetrate from the bottom or top surface of the circuit board 100 without penetrating the entire circuit board 100. The buried hole is buried in the circuit board 100, but is not conducted to the outer surface.

Although the traditional coplanar waveguide plays a certain role in reducing the dielectric loss of the transmission line, larger electric field components are concentrated in the dielectric material of the circuit board. In order to further reduce the transmission line loss, a slot can be arranged between the two sides of the transmission line of the coplanar waveguide and the ground plane (ground wire) to remove part of the medium, so that the medium loss of the transmission line can be greatly reduced. Fig. 21-24 show a circuit board 100 that reduces the dielectric loss of a transmission line by providing slots.

Fig. 21 is a schematic structural diagram of another example of the circuit board 100 according to the embodiment of the present application. Fig. 22 is an exploded view of the circuit board 100 shown in fig. 21. Fig. 23 is a top view and a bottom view of the circuit board 100 shown in fig. 21. Fig. 24 is a cross-sectional view from the BB view in fig. 21. Here, part (a) in fig. 23 is a top view of the circuit board 100, and part (b) in fig. 23 is a bottom view of the circuit board 100.

As shown in fig. 21-24, a dielectric slot 150 is further disposed on the dielectric substrate 110, and the dielectric slot 150 is located between the transmission line segment 131a and the second ground 132. By arranging the dielectric slot 150, part of the dielectric between the transmission line segment 131a and the second ground 132 can be excavated, so that the electric field generated by the transmission line segment 131a can be more distributed in the air, and the distribution of the electric field in the dielectric is reduced, thereby further reducing the dielectric loss of the transmission line and improving the transmission quality of signals.

As shown in fig. 22, fig. 23 (a), and fig. 23 (b), the dielectric slot 150 needs to be arranged in a plurality of spaced-apart slots "in a" slot-by-slot "manner, that is, the dielectric slot 150 is arranged between the transmission line segment 131a and the second ground 132, and the dielectric is reserved where the connection bridge 134 needs to be arranged, so that the connection bridge 134 can be arranged on the dielectric substrate 110 by printing a conductor pattern.

Further, the medium slot 150 is a strip-shaped slot and penetrates through both sides of the medium substrate 110, that is, the medium slot 150 is a through slot penetrating through both sides of the medium substrate 110, and the medium slot 150 extends along the length direction of the transmission line segment 131a. Through the arrangement, more media can be excavated, the distribution of an electric field in the media is reduced as much as possible, the dielectric loss of the transmission line can be further reduced, and the transmission quality of signals is improved.

Alternatively, in other embodiments, the dielectric slot 150 may also be a blind slot, in which case the dielectric slot 150 does not penetrate through both sides of the dielectric substrate 110.

Further, the distance between the edge of the slot of the dielectric slot 150 and each metal pattern of the second conductive pattern layer 130 is 0.05-0.3 mm. Specifically, the distance between the slot edge of the medium slot 150 and the transmission line segment 131a, the second ground 132, or the connection bridge 134 is 0.05 to 0.3 mm. For example, it may be 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.2 mm, or the like.

Fig. 25 is a schematic structural diagram of another example of the circuit board 100 according to the embodiment of the present application. Fig. 26 is an exploded view of the circuit board 100 shown in fig. 25. Fig. 27 is a top view and a bottom view of the circuit board 100 shown in fig. 25. Fig. 28 is a cross-sectional view taken from the perspective CC of fig. 25. Here, part (a) in fig. 27 is a top view of the circuit board 100, and part (b) in fig. 27 is a bottom view of the circuit board 100.

As shown in fig. 25-28, in the embodiment of the present application, a first conductive sidewall 151 is disposed on a groove wall of the dielectric slot 150 adjacent to one side of the transmission line segment 131a, and the transmission line segment 131a is electrically connected to the first signal line 121 through the first conductive sidewall 151. A second conductive sidewall 152 is disposed on a wall of the dielectric slot 150 adjacent to one side of the second ground trace 132, the second conductive sidewall 152 is electrically isolated from the first conductive sidewall 151, and the second ground trace 132 is electrically connected to the first ground trace 122 through the second conductive sidewall 152.

Through the above arrangement, on one hand, the medium slot 150 can be opened as large as possible, the edge of the slot of the medium slot 150 can be close to the edge of the metal pattern, so that in the region between the second signal line 131 and the second ground line 132, except for the part covered by the connecting bridge 134, a small amount of medium is remained, almost all the medium of the rest part is removed, the main component of the electric field is distributed in the air, and therefore, the transmission line loss caused by the medium can be reduced to the greatest extent.

On the other hand, the first conductive sidewall 151 is electrically connected to the signal line of the double-layer coplanar waveguide, the second conductive sidewall 152 is electrically connected to the ground line of the double-layer coplanar waveguide, and the first conductive sidewall 151 and the second conductive sidewall 152 are close to and opposite to each other, so that the area opposite to the ground line of the signal line can be increased, the current distribution in the line is more uniform, the conductor loss is reduced, and the impedance of the transmission line is reduced.

Further, as shown in fig. 26 and fig. 28, in the embodiment of the present application, since the first conductive sidewall 151 realizes electrical connection between signal lines on both sides of the dielectric substrate 110, and the second conductive sidewall 152 realizes electrical connection between ground lines on both sides of the dielectric substrate 110, the metalized via 140 in the foregoing embodiment can be omitted. Thereby saving production processes and production costs. The first conductive sidewall 151 and the second conductive sidewall 152 are electrically isolated from each other, so that one dielectric slot 150 simultaneously realizes electrical connection between the signal line and the ground line on both sides of the dielectric substrate 110.

In the embodiment of the present invention, the manufacturing process (i.e., the metallized sidewall) of the first conductive sidewall 151 and the second conductive sidewall 152 in the dielectric trench 150 is substantially compatible with the manufacturing process of the existing double-sided board or multi-layer board, and no additional manufacturing process is required, so that the implementation cost is close to zero.

Fig. 29 is a flow chart illustrating a process of fabricating a metalized sidewall. As shown in part (a) of fig. 29, a substrate is first provided, which has a surface provided with a complete metal thin layer (e.g., a copper foil layer formed by electroplating), and the substrate may be a double-sided board (i.e., including only one dielectric substrate) or a multi-layer board (i.e., including a plurality of dielectric substrates) on which inner layer patterning and lamination have been completed. As shown in part (b) of fig. 29, metallization drilling and metallization grooving are performed at predetermined positions of the substrate by a drill. Electroplating is performed within the completed hole and trench, as shown in part (c) of fig. 29, so that a thin layer of metal adheres to the walls of the hole and the trench walls, with the dashed lines indicating sidewall metallization. As shown in fig. 29 (d), a non-metalized drilling is performed to remove the plated hole walls at both ends of the metalized groove wall, so as to form the two electrically isolated first conductive sidewalls 151 and second conductive sidewalls 152. As shown in part (e) of fig. 29, excess metal on the substrate surface is finally removed by an etching process to form a metal pattern.

On the other hand, the embodiment of the application also provides an antenna structure. Fig. 30 is a schematic structural diagram of an antenna structure provided in the present application. As shown in fig. 30, the antenna structure provided in the embodiment of the present application includes an antenna unit 200 and the circuit board 100 provided in any one of the foregoing embodiments, the antenna structure is a directional antenna, the antenna unit 200 is disposed on one side of the circuit board 100, and the circuit board 100 forms a reflection plate of the antenna unit 200.

Alternatively, the antenna unit 200 may be a dipole antenna.

Alternatively, the antenna unit 200 may include a plurality and be arranged in an array on the circuit board 100.

Alternatively, the antenna unit 200 is electrically connected to the circuit board 100, for example, a transmission line structure on the circuit board 100 may be used as a feeder of the antenna unit 200.

Because the circuit board 100 provided by the foregoing embodiment ensures the integrity and closure of the ground plane (or does not damage the integrity of the ground plane), and can reduce electromagnetic radiation interference generated by the circuit board 100 on external components, the circuit board 100 can be used as a reflector of a directional antenna without affecting the directional diagram performance of the antenna. A specific simulation example is described below.

In the present simulation example, the antenna unit 200 is a dipole antenna, the circuit board 100 shown in fig. 25 to 28 serves as a reflector of the antenna unit 200, the length of the transmission line is 150mm, and the same simulation scenario as that in fig. 10 is adopted, except that the conventional double-layer coplanar waveguide transmission line structure is replaced by the double-layer coplanar waveguide transmission line structure with the connection bridge 134 provided in the embodiment of the present application.

Fig. 31 is a radiation pattern of an antenna structure provided in an embodiment of the present application. As can be seen from comparing fig. 21 with fig. 6, the antenna pattern is not significantly degraded, because the connection bridge 134 prevents a slot with a large length from being formed on the ground plane, thereby ensuring the closure and integrity of the ground plane.

Since the antenna structure adopts the circuit board 100 provided by the above embodiment, the antenna structure also has the technical effect corresponding to the circuit board 100, which is not described herein again.

In another aspect, an embodiment of the present application further provides an electronic device, where the electronic device includes a housing and the circuit board 100 provided in any of the foregoing embodiments, and the circuit board 100 is located in the housing.

In this case, the electronic device further includes the antenna unit 200, the antenna unit 200 is disposed on one side of the circuit board 100, and the circuit board 100 forms a reflection plate of the antenna unit 200. That is, the electronic device may further include the antenna structure provided in the foregoing embodiment, and the antenna structure is disposed in the housing.

Since the electronic device adopts the circuit board 100 provided in the above embodiment, the electronic device also has the technical effect corresponding to the circuit board 100, which is not described herein again.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A circuit board, comprising:

a dielectric substrate (110) made of an insulating material;

a first conductive pattern layer (120) provided on one side of the dielectric substrate (110), the first conductive pattern layer (120) including a first signal line (121);

the second conductive pattern layer (130) is arranged on the other side of the dielectric substrate (110), and the second conductive pattern layer (130) comprises a second signal line (131) and two second grounds (132) which are arranged on two sides of the second signal line (131) at intervals;

the second signal line (131) comprises a plurality of transmission line segments (131 a) arranged in a column, a fracture (133) is arranged between two adjacent transmission line segments (131 a), the second conductive pattern layer (130) further comprises a connecting bridge (134) electrically isolated from the second signal line (131), the connecting bridge (134) is positioned in the fracture (133) and electrically connected with two second ground lines (132), and each transmission line segment (131 a) is electrically connected with the first signal line (121).

2. The circuit board according to claim 1, wherein the connection bridge (134) and the interruption (133) are each provided in plurality, and each connection bridge (134) is located in the interruption (133).

3. The circuit board according to claim 2, wherein the number of the connecting bridges (134) and the fractures (133) is equal, and a plurality of the connecting bridges (134) and a plurality of the fractures (133) correspond to one another.

4. A circuit board according to any of claims 1-3, characterized in that the length of the transmission line segment (131 a) is less than 0.5 times the wavelength of the electromagnetic wave signal transmitted by the second signal line (131).

5. The circuit board according to any of claims 1-4, wherein each transmission line segment (131 a) is electrically connected to the first signal line (121) by a metallized via (140).

6. The circuit board according to any one of claims 1 to 4, wherein the first conductive pattern layer (120) further comprises two first ground lines (122) disposed at both sides of the first signal line (121) with a space therebetween, and the second ground line (132) is electrically connected to the first ground lines (122).

7. The circuit board of claim 6, wherein the dielectric substrate (110) further has a dielectric slot (150) disposed thereon, and the dielectric slot (150) is located between the transmission line segment (131 a) and the second ground (132).

8. The circuit board of claim 7, wherein the dielectric slot (150) is a strip-shaped slot and penetrates through two sides of the dielectric substrate (110), and the dielectric slot (150) is arranged to extend along the length direction of the transmission line segment (131 a).

9. The circuit board of claim 8, wherein a first conductive sidewall (151) is disposed on a wall of the dielectric slot (150) adjacent to a side of the transmission line segment (131 a), and the transmission line segment (131 a) is electrically connected to the first signal line (121) through the first conductive sidewall (151);

and a second conductive side wall (152) is arranged on the groove wall of the medium groove (150) on one side adjacent to the second ground wire (132), the second conductive side wall (152) is electrically isolated from the first conductive side wall (151), and the second ground wire (132) is electrically connected with the first ground wire (122) through the second conductive side wall (152).

10. The circuit board of claim 6, wherein the second ground (132) is electrically connected to the first ground (122) by a metalized via (140).

11. The circuit board according to any one of claims 7 to 9, characterized in that the distance between the slot edge of the dielectric slot (150) and the transmission line segment (131 a), the second ground line (132) or the connection bridge (134) is 0.05 to 0.3 mm.

12. The circuit board of claim 5, wherein the metalized via (140) is a through hole, a blind hole, or a buried hole.

13. The circuit board according to any one of claims 1 to 12, wherein the circuit board is a double-sided board.

14. The circuit board according to any one of claims 1 to 12, wherein the circuit board is a multilayer board having a plurality of board bodies, and the dielectric substrate (110) is any one of the plurality of board bodies.

15. The circuit board according to any one of claims 1 to 14, wherein the second conductive pattern layer (130) is a metal layer made by an etching process.

16. An antenna arrangement, characterized in that it comprises an antenna element (200) and a circuit board according to any one of claims 1-15, said antenna element (200) being arranged on one side of said circuit board, said circuit board constituting a reflector plate of said antenna element (200).

17. An electronic device comprising a housing and a circuit board according to any of claims 1-15, the circuit board being located within the housing.

18. The electronic device of claim 17, further comprising an antenna unit (200) within the housing, the antenna unit (200) being provided on a side of the circuit board, the circuit board constituting a reflector plate of the antenna unit (200).