WO2023016024A1 - 电路板、天线结构及电子设备 - Google Patents

电路板、天线结构及电子设备 Download PDF

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Publication number
WO2023016024A1
WO2023016024A1 PCT/CN2022/093556 CN2022093556W WO2023016024A1 WO 2023016024 A1 WO2023016024 A1 WO 2023016024A1 CN 2022093556 W CN2022093556 W CN 2022093556W WO 2023016024 A1 WO2023016024 A1 WO 2023016024A1
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Prior art keywords
circuit board
transmission line
signal line
dielectric substrate
conductive pattern
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PCT/CN2022/093556
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English (en)
French (fr)
Inventor
罗兵
覃雯斐
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华为技术有限公司
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Publication of WO2023016024A1 publication Critical patent/WO2023016024A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P3/00—Waveguides; Transmission lines of the waveguide type
    • H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P3/00—Waveguides; Transmission lines of the waveguide type
    • H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
    • H01P3/08—Microstrips; Strip lines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details

Definitions

  • the present application relates to the technical field of communication, and more specifically, relates to a circuit board, an antenna structure and electronic equipment.
  • the circuit board is the basic carrier for the electrical connection of electronic components, and its main function is to support electronic components and interconnect electronic components.
  • signal transmission between different electronic components on the circuit board is usually realized through transmission lines.
  • a transmission line is a linear structure that carries electromagnetic energy. It is an important part of telecommunications systems and is used to transmit radio frequency signals carrying information from one point to another.
  • commonly used transmission lines include structures such as microstrip lines, striplines, single-layer coplanar waveguides, and double-layer coplanar waveguides.
  • Double-layer coplanar waveguide is a commonly used transmission line structure. Compared with transmission line structures such as microstrip line or stripline, double-layer coplanar waveguide can reduce the distribution of electric field in the dielectric substrate, and then can suppress the medium to a certain extent. loss problem.
  • the ground plane of the circuit board is composed of the two ground wires and the signal wire of the coplanar waveguide at this time, since there are long slots (gap) between the signal wire and the ground wires on both sides, the The integrity of the ground plane of the circuit board is compromised, resulting in poor sealing of the circuit board and poor shielding performance against electromagnetic waves.
  • the above reasons make it easy for the electromagnetic components on the circuit board to "couple" with external components, resulting in poor anti-interference performance of the circuit board itself, and it is also easy to generate radiation interference to external components.
  • the application provides a circuit board, antenna structure and electronic equipment.
  • the structure of the coplanar waveguide on the circuit board By improving the structure of the coplanar waveguide on the circuit board, the length of the slot on the ground plane is reduced, and the integrity and sealing of the ground plane are ensured. Therefore, the anti-interference performance of the circuit board is improved, and the electromagnetic radiation generated by the circuit board to external components is reduced.
  • a circuit board including: a dielectric substrate made of insulating material; a first conductive pattern layer disposed on one side of the dielectric substrate, and the first conductive pattern layer includes a first signal line;
  • the second conductive pattern layer is arranged on the other side of the dielectric substrate, and the second conductive pattern layer includes a second signal line and two second ground lines arranged at intervals on both sides of the second signal line;
  • the second signal line includes a plurality of transmission line segments arranged in a row, and there is a break between two adjacent transmission line segments, and the second conductive pattern layer also includes a connecting bridge electrically isolated from the second signal line, The connecting bridge is located in the opening and is electrically connected to the two second ground wires, and each of the transmission line segments is electrically connected to the first signal wire.
  • the second conductive pattern layer includes a second signal line and two second ground lines that 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 into a plurality of transmission line segments, and there is a break between two adjacent transmission line segments, and a connecting bridge connecting the second ground wires on both sides is arranged in the break.
  • the present application can reduce the length of the slot between the second signal line and the second ground line by arranging the connecting bridge, which increases the setting area of the conductive pattern on the dielectric substrate (that is, increases the coverage area of the ground plane), and improves The integrity and sealing of the ground plane are improved, and the shielding performance of the ground plane to electromagnetic waves is improved.
  • the electromagnetic components on the circuit board are not easy to generate electromagnetic waves "coupling" with external components, thereby improving the anti-interference performance of the circuit board and reducing the impact of the circuit board on external components. The effects of electromagnetic radiation produced.
  • the second conductive pattern layer in the embodiment of the present application can be integrated on the dielectric substrate through a process such as planar printing, which maintains the advantages of the traditional coplanar waveguide transmission line in miniaturization and easy integration with chips.
  • the setting of the connection bridge does not require any additional process, and has an implementation cost close to zero.
  • the circuit board provided by the embodiment of the present application has the advantages of small size, high integration and low cost, and has wide application space in electronic products.
  • the circuit board provided in the embodiment of the present application adopts a coplanar waveguide transmission line structure to transmit radio frequency signals.
  • the main electric field can be distributed in the air, thereby reducing the electric field in the air.
  • the distribution in the dielectric substrate can suppress the problem of dielectric loss to a certain extent, thereby realizing low-loss transmission of radio frequency signals and improving the quality of signal transmission.
  • the signal electric field is mainly distributed in the air, the delay per unit length is small, which can reduce the phase winding and realize low-delay signal transmission.
  • the circuit board includes but is not limited to: bottom board, mid-plane, backplane, flexible circuit board, rigid circuit board, rigid-flex board, terminal circuit board, package carrier board, low-temperature co-fired ceramic substrate or high-temperature co-fired ceramic Substrate etc.
  • the package substrate may be a system-in-package substrate, a single-chip package substrate, a multi-chip package substrate, or a ball grid array package substrate.
  • the dielectric substrate is made of hard insulating material.
  • the material constituting the dielectric substrate may be at least one of ceramic material, resin material, glass material, or hard plastic.
  • the dielectric substrate may be made of at least one material selected from alumina ceramics, aluminum nitride ceramics, phenolic resin, epoxy resin, brominated epoxy resin, polyester or polytetrafluoroethylene.
  • the dielectric substrate is made of flexible insulating material.
  • the dielectric substrate may be made of at least one material among polyester, polyimide, fluorocarbon, or aromatic polyamide.
  • the circuit board can be applied to foldable electronic devices (such as foldable mobile phones).
  • both the connecting bridge and the fracture are multiple, and each of the connecting bridges is located in the fracture.
  • the number of breaks may be greater than, equal to or less than the number of connecting bridges.
  • the number of connecting bridges arranged in different fractures may be the same or different.
  • connection bridge only one connection bridge, or multiple connection bridges, or no connection bridge may be provided in the fracture, which is not limited in this application.
  • the number of fractures is greater than the number of connecting bridges, and multiple connecting bridges are arranged in the multiple fractures in one-to-one correspondence, and since there are more fractures, no connecting bridges may be provided in the remaining fractures.
  • the number of the connection bridges is equal to the number of the fractures, and a plurality of the connection bridges corresponds to a plurality of the fractures one by one.
  • 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.
  • each transmission line segment is electrically connected to the first signal line through a metallized via hole.
  • the first conductive pattern layer further includes two first ground lines arranged at intervals on both sides of the first signal line, and the second ground line is electrically connected to the first ground line. connect.
  • a dielectric slot is further provided on the dielectric substrate, and the dielectric slot is located between the transmission line segment and the second ground wire.
  • the dielectric slot By setting the dielectric slot, part of the medium between the transmission line segment and the second ground wire can be excavated, so that the electric field generated by the transmission line segment can be more distributed in the air, and the distribution of the electric field in the medium can be reduced , which can further reduce the dielectric loss of the transmission line and improve the transmission quality of the signal.
  • the medium groove is a strip groove and runs through both sides of the medium substrate (that is, the medium groove is a through groove at this time), and the medium groove is along the transmission line segment The length direction extension setting.
  • the dielectric slot may also be a blind slot, and at this time, the dielectric slot does not penetrate through both sides of the dielectric substrate.
  • the distance between the notch edge of the dielectric slot and the transmission line segment, the second ground wire or the connecting bridge is 0.05-0.3 mm.
  • it may be 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, or 0.2 mm.
  • a first conductive side wall is provided on the slot wall of the dielectric slot adjacent to the transmission line segment, and the transmission line segment passes through the first conductive side wall and the first signal wire electrical connection;
  • a second conductive side wall is provided on the side of the dielectric slot adjacent to the second ground wire, and the second conductive side wall is electrically isolated from the first conductive side wall, and the second conductive side wall is electrically isolated from the first conductive side wall.
  • the second ground wire is electrically connected to the first ground wire through the second conductive sidewall.
  • the opening of the dielectric slot can be made as large as possible, and the edge of the slot of the dielectric slot can be close to the edge of the metal pattern, so that the area between the second signal line and the second ground line, except for the connection bridge covered Except for a small amount of dielectric in the remaining part, the rest of the dielectric is almost completely removed, and the main component of the electric field is distributed in the air, so the transmission line loss caused by the dielectric can be minimized.
  • the first conductive sidewall is electrically connected to the signal line of the double-layer coplanar waveguide
  • the ground wire of the second conductive sidewall is electrically connected to the double-layer coplanar waveguide
  • the first conductive sidewall and the second conductive sidewall are connected to each other Close to and opposite to each other, thereby increasing the facing area of the signal line and the ground line, and making the current distribution in the line more uniform, thereby reducing conductor loss and reducing the impedance of the transmission line.
  • the second ground wire is electrically connected to the first ground wire through a metallized via hole.
  • the circuit board is double-sided.
  • the circuit board is a multi-layer board having multiple board bodies, and the dielectric substrate is any one of the multiple board bodies.
  • the one plate may be only one plate between the first conductive pattern layer and the second conductive pattern layer, and in this case, the one plate is the dielectric substrate.
  • the dielectric substrate is one of the multiple boards at this time.
  • the metallized via hole is a through hole, a blind hole or a buried hole.
  • the second conductive pattern layer is a metal layer made by an etching process.
  • an antenna structure including an antenna unit and a circuit board provided by any possible design in the aforementioned first aspect, the antenna unit is arranged on one side of the circuit board, and the circuit board A reflection plate constituting the antenna unit.
  • the circuit board provided in the first aspect ensures the integrity and sealing of the ground plane (or in other words, does not destroy the integrity of the ground plane), it can reduce the electromagnetic radiation interference of the circuit board to external components, so the circuit board can be used as A reflector for directional antennas is used without affecting the antenna's pattern performance.
  • the antenna structure may be an active antenna or a passive antenna.
  • the antenna unit may be a dipole antenna.
  • multiple antenna units may be included and arranged on the circuit board in the form of an array.
  • the antenna unit is electrically connected to the circuit board, for example, the transmission line structure on the circuit board can be used as a feeder for the antenna unit.
  • an electronic device including a housing and a circuit board provided by any possible design in the aforementioned first aspect, the circuit board is located in the housing.
  • the electronic device may be a handheld device, vehicular device, wearable device, computing device, or other processing device connected to a wireless modem.
  • the electronic device may be a mobile phone, a tablet computer, a laptop computer, a smart watch, a smart bracelet, smart glasses, or a smart TV (smart screen).
  • the electronic device may be a communication device, such as a base station or a radar.
  • the electronic device further includes an antenna unit located in the casing, the antenna unit is disposed on one side of the circuit board, and the circuit board constitutes a reflector of the antenna unit.
  • Figure 1 shows a schematic diagram of the structures of various types of transmission lines.
  • FIG. 2 shows a schematic diagram of the principle of loss caused by the microstrip line during signal transmission.
  • 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 through coplanar waveguides.
  • Figure 5 shows three commonly used 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 diagram of the antenna structure shown in FIG. 6 .
  • FIG. 8 is a schematic structural diagram of an antenna structure with a microstrip line arranged on a circuit board.
  • FIG. 9 is a radiation pattern diagram of the antenna structure shown in FIG. 8 .
  • Fig. 10 is a schematic structural diagram of an antenna structure with a double-layer coplanar waveguide arranged on a circuit board.
  • FIG. 11 is a radiation pattern diagram of the antenna structure shown in FIG. 10 .
  • FIG. 12 is a schematic structural diagram of a circuit board provided by 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 perspective of AA in FIG. 12 .
  • FIG. 16 is a schematic structural diagram of another example of the circuit board provided by 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 cross-sectional view of another example of the circuit board provided by the 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 the circuit board provided by the 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 perspective of BB in FIG. 21 .
  • FIG. 25 is a schematic structural diagram of another example of the circuit board provided by 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 viewed from CC in FIG. 25 .
  • FIG. 29 is a schematic flow chart of the fabrication process of the metallized sidewall.
  • Fig. 30 is a schematic structural diagram of the antenna structure provided by the present application.
  • Fig. 31 is a radiation pattern diagram of the antenna structure provided by the embodiment of the present application.
  • Dielectric substrate 22. Reference ground plane; 23. Microstrip line; 2H, magnetic field; 2E, electric field;
  • Dielectric substrate 51. Dielectric substrate; 52. Dipole antenna; 53. Microstrip line; 54. Coplanar waveguide; 55. Metallized via hole;
  • Circuit board 110. Dielectric substrate; 120. First conductive pattern layer; 121. First signal line; 122. First ground line; 130. Second conductive pattern layer; 131. Second signal line; 131a. Transmission line Section; 132, second ground wire; 133, fracture; 134, connecting bridge; 140, metallized via; 150, medium slot; 151, first conductive side wall; 152, second conductive side wall; 160, the first The third conductive pattern layer; 170, the fourth conductive pattern layer.
  • the terms “installation” and “connection” should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated Ground connection; it can be mechanical connection, electrical connection or mutual communication; it can be direct connection or indirect connection through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components.
  • installation and “connection” should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated Ground connection; it can be mechanical connection, electrical connection or mutual communication; it can be direct connection or indirect connection through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components.
  • orientation or positional relationship indicated by the terms “upper”, “lower”, “side”, “front”, “rear”, “inner”, “outer” etc.
  • the orientation or positional relationship is only for the convenience of describing the application and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as limiting the application .
  • the circuit board is the basic carrier for the electrical connection of electronic components, and its main function is to support electronic components and interconnect electronic components.
  • the circuit board makes the circuit miniaturized and intuitive, and plays an important role in the mass production and optimized layout of the circuit. Divided according to the number of circuit layers, circuit boards usually include single-sided boards, double-sided boards and multi-layer boards.
  • the single-sided board is the most basic circuit board.
  • the components are concentrated on one side of the dielectric substrate, and the wires are concentrated on the other side of the dielectric substrate.
  • a double-sided board is a circuit board in which wiring (copper cladding) is performed on both sides of a dielectric substrate. At this time, the wires on both sides of the dielectric substrate form a conductive pattern layer, and the dielectric substrate forms an insulating layer between the two conductive pattern layers.
  • Multilayer circuit boards include multiple conductive pattern layers (3 layers and above) and multiple insulating layers (that is, multiple dielectric substrates), and two adjacent conductive pattern layers are separated by insulating layers, and adjacent The two conductive pattern layers are electrically connected through conductive vias (also called metallized vias).
  • a transmission line is a linear structure that transmits electromagnetic energy. It is an important part of a telecommunication system and is used to transport electromagnetic waves (radio frequency signals) carrying information from one point to another along the route specified by the transmission line.
  • commonly used transmission lines include microstrip, stripline, coplanar waveguide (CPW), grounded coplanar waveguide (GCPW), substrate integrated waveguide ( substrate integrated waveguide, SIW), coaxial cable, waveguide, twisted pair and other structures.
  • FIG. 1 shows a schematic diagram of the structures of various types of transmission lines.
  • 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 (such as copper) and can be used to propagate radio frequency
  • the dielectric substrate 11 is made of an insulating medium, which can function as electrical isolation, and a ground plane 13 is provided on the bottom surface of the dielectric substrate 11 .
  • the ground plane here is usually also referred to as reference ground, reference ground plane or ground plane, etc., and is usually electroplated copper foil (copper skin).
  • the stripline is a strip-shaped signal line 12 between the bonding surfaces of two dielectric substrates 11, and the surfaces of the two dielectric substrates 11 facing away from each other are respectively arranged
  • the metallized via hole 15 is formed by opening a through hole connecting both sides on the dielectric substrate 11, and disposing a metal conductive material in the through hole to form the metallized via hole 15, and the two ends of the metal conductive material are respectively electrically connected to the ground planes 13 on both sides. .
  • the coplanar waveguide is also called a coplanar microstrip transmission line, and includes three strip conductors formed on the top surface of the dielectric substrate 11, the three strip conductors are parallel to each other, and interval setting.
  • the strip conductor in the middle constitutes a signal line 12 for transmitting signals
  • the two strip conductors on both sides constitute two ground wires 14 .
  • the ground wire 14 can be designed as wide as possible, so that the two ground wires 14 and the signal wire 12 together form a "ground plane" with a groove (the gap between the signal wire 12 and the ground wire 14). This ground plane can act as a reflective surface for the antenna.
  • the grounded coplanar waveguide is also called back-coated metal coplanar waveguide.
  • a ground plane 13 is provided, and the ground plane 13 is electrically connected to the ground wire 14 on the other side through the metallized via hole 15 .
  • the setting of the ground plane 13 not only strengthens the mechanical strength of the dielectric substrate 11 , but also provides a good heat dissipation medium for active devices.
  • transmission lines such as microstrip line, stripline, GCPW, and CPW have the characteristics of compact structure and high integration, and are easy to adopt It is produced by planar printing process, so it is generally used in planar circuits such as printed circuit boards (PCB), chips, and packaging substrates.
  • This type of transmission line is easy to integrate with the circuit, but generally has a large loss.
  • Parts (e), (f) and (g) in Fig. 1 are structural schematic diagrams of waveguide, twisted pair and coaxial cable respectively. Transmission line structures such as waveguide, twisted pair, and coaxial cable are generally used for signal connections between devices or modules. Such transmission lines have low loss, but are too bulky to be integrated with circuits.
  • microstrip lines, striplines, GCPW, and CPW transmission lines have the advantages of small size, high integration, and easy integration with chips or circuits, there are also great shortcomings, that is, large losses, especially in transmission. In the case of high-frequency signals, loss becomes a key issue restricting the application of this type of transmission line.
  • the main reason for the loss is that the conductors of these types of transmission line structures are printed and attached to the dielectric substrate.
  • the dielectric substrate During the signal transmission process, most of the electric field is distributed in the dielectric substrate, because the molecules of the insulating medium that make up the dielectric substrate will be in the alternating electric field Under the action of vibration, part of the electromagnetic energy is converted into heat energy, which leads to the reduction of signal energy at the output point of the transmission line and the formation of dielectric loss (that is, the loss caused by the insulating medium of the dielectric substrate).
  • FIG. 2 shows a schematic diagram of the principle of loss caused by the microstrip line during signal transmission.
  • the top surface of the dielectric substrate 21 is provided with a microstrip line 23
  • the bottom surface is provided with a reference ground plane 22 .
  • the microstrip line 23 is powered on, for example, when transmitting a high-frequency signal
  • the peripheral side of the microstrip line 23 forms an electric field 2E (the solid line arrow part in FIG. 2 ) and a magnetic field 2H (the dotted line part in FIG. 2 ), It can be seen from FIG.
  • the loss caused by the medium is related to the characteristics of the material on the one hand, determined by the microscopic molecular structure of the material; on the other hand, it is related to the frequency of the transmitted signal. The higher the frequency, the greater the loss.
  • the dielectric loss is usually reduced from three aspects: improving the material properties of the dielectric substrate, reducing the distribution of the electric field in the dielectric substrate, and adopting a coplanar waveguide structure. These three methods are introduced respectively below.
  • the first method that can be adopted is to improve the characteristics of the material that constitutes the dielectric substrate.
  • many manufacturers on the market have launched a series of PCB board products for high-frequency signal applications. These products change the microscopic properties of the material. The molecular structure realizes the reduction of dielectric loss.
  • Fig. 3 is a structural schematic diagram of a suspended stripline and a suspended microstrip line, wherein part (a) in Fig. 3 shows the basic structure of a suspended stripline, and part (b) in Fig. 3 shows The basic structure of the suspended microstrip line.
  • the suspended stripline structure includes two metal plates 31 arranged at intervals relative to each other, two metal side walls 32 located between the two metal plates 31 and arranged at intervals, the two The metal plate 31 and the two metal side walls 32 together define a cavity 33 , and the metal signal wire 34 is suspended in the cavity 33 .
  • the suspended microstrip line structure includes a metal plate 31, a metal signal line 34 is suspended above the metal plate 31, and there is a gap 35 between the metal plate 31 and the metal signal line 34. .
  • the metal signal line 34 and the dielectric substrate can be separated from each other (an air layer is formed in the middle). Since the metal signal line 34 has a certain distance from the dielectric substrate, the electric field formed by the metal signal line 34 is mostly distributed. in the air, while minimizing the distribution of the electric field in the medium.
  • the suspension line structure achieves the purpose of reducing the dielectric loss, because the signal line and the ground plane are separated, they are not printed and attached to the same dielectric substrate, which leads to an increase in structural complexity, and additional reflectors and support components need to be added. Integrated The speed is also greatly reduced, and the cost is also greatly increased.
  • the prior art with the patent publication number CN106785284A discloses a suspended stripline structure formed by stacking multilayer PCBs. This structure realizes the suspension of striplines through 5-layer PCBs, and the cost is relatively lower than that of ordinary double-sided PCBs. The rise is more than 5 times, and the thickness is more than 2 times.
  • the structure of the suspended microstrip line shown in part (a) of Figure 3 is simpler, but in order to realize the suspension of the signal conductor, a complex support structure is also required, and at the same time, in order to reduce the manufacturing difficulty and reduce the assembly error to the suspension Due to the influence of the impedance of the microstrip line, the distance between the metal signal line 34 and the metal plate 31 is generally set farther away, which also leads to poor sealing of the suspended microstrip line, which is prone to external radiation (forming external interference and increasing loss). Close to issues such as line-to-line coupling.
  • FIG. 4 is a schematic diagram of the principle of reducing dielectric loss through coplanar waveguides. As shown in Figure 4, one side of the dielectric substrate 41 is provided with a coplanar waveguide through printing and other processes, and the coplanar waveguide includes a signal line 42, and two ground lines 43 arranged in parallel on opposite sides of the signal line 42, the ground line 43 and the signal line 42 are spaced apart from each other.
  • an electric field 4E is formed around the signal line 42 (the solid line arrow in FIG. 4 ). It can be seen from FIG. 2 that the direction of the electric field 4E passes from the signal line 42 to the ground line 43 after passing through the gap (slot) formed between the signal line 42 and the ground line 43, instead of being perpendicular to the dielectric substrate 41, so that a part of the electric field 4E It is located in the dielectric substrate 41, while the other 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, thereby reducing the dielectric loss.
  • Figure 5 shows three commonly used coplanar waveguide transmission line structures.
  • part (a) in FIG. 5 is a cross-sectional view of a single-layer coplanar waveguide transmission line structure.
  • Part (b) in FIG. 5 is a cross-sectional view of a single-layer coplanar waveguide transmission line structure with reference ground.
  • Part (c) of FIG. 5 is a cross-sectional view of a double-layer coplanar waveguide transmission line structure.
  • one of the most commonly used methods is to reduce the dielectric loss by using a single-layer coplanar waveguide.
  • the single-layer coplanar waveguide reduces the distribution of the electric field in the medium to a certain extent, due to the small direct area between the signal line 42 and the ground line 43, the impedance of the transmission line is relatively high, and it is also affected by the skin effect.
  • the current distribution is concentrated on the edge of the microstrip line, and the conductor loss is increased due to the small current distribution area, so it is not used much in actual electronic products.
  • the coplanar waveguide and the ground plane 44 are arranged on the two opposite sides of the dielectric substrate 41, so that the structure is similar to a microstrip Line, most of the electric field is still distributed in the medium, which has no effect on improving the loss. Its role is to enhance the isolation between the microstrip line and other adjacent transmission lines.
  • two coplanar waveguides are respectively arranged on two opposite sides of a dielectric substrate 41, and two metallized via holes 45 are used to realize two-layer coplanar waveguides.
  • ground plane is required in the circuit board design of high-frequency electronic products, otherwise it will cause problems such as reduced anti-interference performance of the circuit board and increased external interference radiation.
  • the double-layer coplanar waveguide transmission line structure is rarely used in actual electronic products.
  • the problem is that the ground plane of the circuit board is composed of two ground lines 43 and signal lines 42 of the coplanar waveguide.
  • the signal line 42 and the two sides There are slots with a large length between the ground wires 43, thereby destroying the integrity of the ground plane of the circuit board, resulting in poor sealing of the circuit board and poor shielding performance for electromagnetic waves.
  • Electromagnetic waves generated by electromagnetic components such as coplanar waveguides on the circuit board are easy to emit to the outside of the circuit board through slots to cause electromagnetic interference to other components, and electromagnetic waves generated by other components are also easy to cause electromagnetic components on the circuit board through slots. Influence.
  • the above-mentioned problems existing in the double-layer coplanar waveguide transmission line structure will be further illustrated below through specific simulation examples.
  • 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 diagram of the antenna structure shown in 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 arranged, and the circuit board constitutes the reflection of the dipole antenna 52.
  • the circuit board includes a dielectric substrate 51, the bottom surface of the dielectric substrate 51 (that is, the side away from the dipole antenna 52) is covered with copper foil, the copper foil on the circuit board is used as the reflective surface of the dipole antenna 52, and the dipole
  • the antennas 52 together form an antenna with a directional radiation function, and its radiation pattern is shown in FIG. 7 .
  • FIG. 8 is a schematic structural diagram of an antenna structure with a microstrip line arranged on a circuit board.
  • FIG. 9 is a radiation pattern diagram of the antenna structure shown in FIG. 8 .
  • a microstrip line 53 with a length of 150 mm is set on the front side of the dielectric substrate 51 (that is, the side facing the dipole antenna 52), At this time, the radiation pattern of the antenna structure is shown in FIG. 9 . Comparing Figures 7 and 9, it can be seen that the addition of the microstrip line 52 does not cause the antenna pattern to deteriorate, because the copper foil on the back of the dielectric substrate 51 is not damaged, and the reflective surface of the dipole antenna 53 is still intact.
  • FIG. 10 is a schematic structural diagram of an antenna structure with a double-layer coplanar waveguide arranged on a circuit board.
  • FIG. 11 is a radiation pattern diagram of the antenna structure shown in FIG. 10 .
  • a coplanar waveguide 54 is respectively arranged on the two sides of the dielectric substrate 51, and a plurality of metallized via holes 55 are used to realize the waveguide on both sides.
  • the length of the coplanar waveguide 54 is 150 mm.
  • the pattern of the antenna is shown in FIG. 11 .
  • double-layer coplanar waveguides can reduce the distribution of electric fields in the dielectric substrate, thereby suppressing the problem of dielectric loss to a certain extent.
  • the ground plane of the circuit board is composed of the two ground wires and the signal wire of the coplanar waveguide at this time, since there are long slots between the signal wire and the ground wires on both sides, the circuit board is damaged. The integrity of the ground plane leads to poor sealing of the circuit board and poor shielding performance against electromagnetic waves.
  • the electromagnetic waves generated by electromagnetic components such as coplanar waveguides on the circuit board are easy to radiate to the outside of the circuit board through the slots to cause interference to other components, and the electromagnetic waves generated by other components are also easy to affect the electromagnetic components on the circuit board through the slots. make an impact. That is to say, the current double-layer coplanar waveguide transmission line structure is easy to cause electromagnetic wave "coupling" between the electromagnetic components on the circuit board and external components, resulting in poor anti-interference performance of the circuit board itself, and it is also easy to cause interference to external components. radiation interference.
  • the embodiment of the present application provides a circuit board, an antenna structure and an electronic device.
  • the length of the slot on the ground plane is reduced, and the stability of the ground plane is improved. Integrity and sealing, thereby improving the anti-interference performance of the circuit board, and reducing the electromagnetic radiation generated by the circuit board to external components.
  • FIG. 12 is a schematic structural diagram of a circuit board 100 provided by 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 perspective of AA in FIG. 12 .
  • the 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 insulating material, and is located between the first conductive pattern layer 120 and the second conductive pattern layer 130, so as to electrically isolate the above two conductive layers.
  • the first conductive pattern layer 120 is patterned on one side of the dielectric substrate 110 , 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 (strip) line with a certain width.
  • the second conductive pattern layer 130 is patterned on the other side of the dielectric substrate 110.
  • the second conductive pattern layer 130 includes a second signal line 131 and two second grounds arranged at intervals on both sides of the second signal line 131.
  • Line 132 The second signal line 131 and the two second ground lines 132 arranged side by side and at intervals jointly form a coplanar waveguide transmission line structure.
  • Both the second signal line 131 and the two second ground lines 132 are metal strip lines with a certain width.
  • the second signal line 131 includes a plurality of transmission line segments 131a (for example, two in the figure) arranged in a row, and there is a break between two adjacent transmission line segments 131a (notch) 133.
  • the break 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 is located in the opening 133 and electrically connected to the two second ground lines 132 .
  • the opening 133 is configured to allow the connection bridge 134 to pass through, and the width of the 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 131 a on both sides of the opening 133 .
  • a metallized via hole 140 is also provided on the dielectric substrate 110 .
  • the metallized via hole 140 connects both sides by opening a through hole on the dielectric substrate 110 , and the through hole It is formed by setting metal conductive material inside (for example, on the wall of the hole).
  • Each of the multiple 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 metallized via hole 140, and the first signal line 121 transmits the radio frequency signal to each A transmission line segment 131a.
  • the second conductive pattern layer 130 includes a second signal line 131 and two second ground lines 132 that together form a coplanar waveguide transmission line structure, and the coplanar waveguide transmission line structure can constitute a circuit board 100' of ground plane.
  • the second signal line 131 is cut into a plurality of transmission line segments 131a, and there is a break 133 between two adjacent transmission line segments 131a, and a connection bridge 134 connecting the second ground lines 132 on both sides is arranged in the break 133 .
  • the present application can reduce the length of the slot between the second signal line 131 and the second ground line 132 by setting the connecting bridge 134, which increases the setting area of the conductive pattern on the dielectric substrate 110 (that is, increases the coverage of the ground plane. area), which improves the integrity and sealing of the ground plane, thereby improving the shielding performance of the ground plane to electromagnetic waves.
  • the electromagnetic components on the circuit board are not easy to generate electromagnetic waves "coupling" with external components, thereby improving the anti-interference performance of the circuit board and reducing the impact of the circuit board on external components. The effects of electromagnetic radiation produced.
  • the second conductive pattern layer 130 in the embodiment of the present application can be integrated on the dielectric substrate 110 by planar printing and other processes, which maintains the advantages of traditional coplanar waveguide transmission lines such as miniaturization and easy integration with chips.
  • the setting of the connecting bridge 134 does not require any additional process, and has an implementation cost close to zero.
  • the circuit board 100 provided by the embodiment of the present application has the advantages of small size, high integration and low cost, and has wide application space in electronic products.
  • the circuit board 100 provided in the embodiment of the present application adopts a coplanar waveguide transmission line structure to transmit radio frequency signals.
  • the main electric field can be distributed in the air, thereby reducing the electric field.
  • the distribution in the dielectric substrate 110 can suppress the problem of dielectric loss to a certain extent, thereby realizing low-loss transmission of radio frequency signals and improving the quality of signal transmission.
  • the delay per unit length is small, which can reduce the phase winding and realize low-delay signal transmission.
  • the circuit board 100 provided by the embodiment of the present application will be further introduced below with reference to the accompanying drawings.
  • the circuit board 100 provided by the embodiment of the present application can be used to transmit high-speed signals. Bonding boards, terminal circuit boards, packaging substrates, low-temperature cofired ceramics (LTCC) substrates or high-temperature cofired ceramics (HTCC) substrates, etc.
  • the package substrate can be a system-in-package (SIP) substrate, a single chip package (SCP) substrate, a multi-chip package (MCP) substrate or a ball grid array (ball grid array) , BGA) package substrate, etc.
  • the dielectric substrate 110 is made of hard insulating material.
  • the material constituting the dielectric substrate 110 may be at least one of ceramic material, resin material, glass material, or hard plastic.
  • the dielectric substrate 110 may be made of at least one material selected from alumina ceramics, aluminum nitride ceramics, phenolic resin, epoxy resin, brominated epoxy resin, polyester, or polytetrafluoroethylene.
  • the dielectric substrate 110 is made of a flexible insulating material.
  • the dielectric substrate 110 may be made of at least one material among polyester, polyimide, fluorocarbon, or aromatic polyamide.
  • the circuit board 100 can be applied to foldable electronic devices (such as foldable mobile phones).
  • the circuit board 100 may be a double-sided board or a multi-layer board, which is not limited in this application.
  • the circuit board 100 is a double-sided board.
  • the circuit board 100 only includes one board body, that is, the dielectric substrate 110.
  • the first conductive pattern layer 120 and the second The conductive pattern layer 130 is respectively disposed on two opposite sides of the dielectric substrate 110 .
  • the circuit board 100 may also be a multi-layer board.
  • the circuit board 100 includes a plurality of boards stacked on top of each other. There is a conductive layer between adjacent boards.
  • the dielectric substrate 110 is the Any one of multiple boards.
  • the first conductive pattern layer 120 and the second conductive pattern layer 130 are disposed on opposite sides of the dielectric substrate 110, and may be disposed directly on the dielectric substrate 110, or through an intermediary (such as at least one board and/or conductive layer) is connected to the dielectric substrate 110 .
  • the top surface (upper surface) of the dielectric substrate 110 is provided with a first conductive pattern layer 120
  • the bottom surface (lower surface) of the dielectric substrate 110 is provided with a second conductive pattern layer 130 .
  • the above two conductive pattern layers can be formed on the surface of the dielectric substrate 110 by printing, etching or other processes.
  • a thin metal layer can be provided on the surface of the dielectric substrate 110 by electroplating and other processes, and then the excess metal on the surface of the dielectric substrate 110 can be removed by etching for patterning, thereby forming the first conductive pattern layer 120 or the second conductive pattern layer 130 .
  • the thin metal layer may be copper foil, aluminum foil, or beryllium copper alloy foil. That is to say, 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 and the second ground line 132 are metal strip lines.
  • the first conductive pattern layer 120 also includes two first ground wires 122 arranged at intervals on both sides of the first signal wire 121, at this time the first signal wire
  • the wire 121 and the two first ground wires 122 jointly constitute another planar waveguide transmission line structure on the circuit board 100 , that is, the circuit board 100 has a double-layer coplanar waveguide transmission line structure.
  • Each of the two second ground wires 132 is electrically connected to the first ground wire 122 on the corresponding side through the metallized via hole 140 .
  • a plurality of metallized via holes 140 are disposed on the dielectric substrate 110 , and the metallized via holes 140 are electrically connected to ground wires or signal wires on both sides.
  • the first signal line 121 and the second signal line 131 are arranged opposite to each other, and the projections of the two on the dielectric substrate 110 are at least partially overlapped, the metallized via hole 140 is perpendicular to the surface of the dielectric substrate 110, and part of the metallized via hole 140 is located In the region where the projections overlap, the first signal line 121 and the second signal line 131 on both sides can be electrically connected.
  • each transmission line segment 131 a is electrically connected to the first signal line 121 through at least one metallized via hole 140 .
  • the first ground line 122 and the second ground line 132 are arranged opposite to each other, and the projections of the two on the dielectric substrate 110 are at least partially overlapped, and a part of the metallized via hole 140 is located in the area where the projections overlap, so as to be able to electrically connect the first ground wires on both sides.
  • the ground wire 122 and the second ground wire 132 ensure that the potentials of the first ground wire 122 and the second ground wire 132 are equal.
  • each metallized via hole 140 may be the same or different, and the cross-sectional shape of the metallized via hole 140 is not limited, for example, it may be circular, square, or strip-shaped.
  • the electrical connection between the ground wires or signal wires on both sides of the dielectric substrate 110 may also be implemented in other ways, which is not limited in this application.
  • the other way may be the metallization groove structure described below.
  • the second conductive pattern layer 130 includes two transmission line segments 131a, and the above two transmission line segments 131a are separated from each other by a fracture 133, and a connecting bridge 134 is arranged in the fracture 133 to connect The bridge 134 electrically connects the two second ground lines 132 on both sides of the second signal line 131 .
  • the width of the second ground line 132 may be greater than the width of the second signal line 131, for example, the second ground line 132 may extend to the edge positions on both sides of the dielectric substrate 110, and the above setting can improve the stability of the ground plane as much as possible. area to improve the shielding effect.
  • FIG. 16 is a schematic structural diagram of another example of the circuit board 100 provided by 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 . Wherein, 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 .
  • the second signal line 131 can also be divided into more transmission line segments 131a, at this time, there are more fractures 133, and more Connect the bridge 134 .
  • each connecting bridge 134 is located in the fracture 133 .
  • more connecting bridges 134 can be set according to local conditions, so as to ensure that the transmission line segment 131a will not be too long, that is, ensure the slot between the transmission line segment 131a and the second ground line 132 The length is not too large, thereby ensuring the integrity and sealing of the ground plane, that is, ensuring that the ground plane can have good shielding performance.
  • excessive slotting length is not conducive to production and processing (too long cutting path of the milling cutter is prone to errors).
  • multiple connecting bridges 134 are provided to shorten the slotting length, which can improve production efficiency and reduce production costs.
  • the number of openings 133 may be greater than, equal to or less than the number of connecting bridges 134 .
  • the number of connecting bridges 134 provided in different openings 133 may be the same or different.
  • connection bridge 134 may be provided in the fracture 133, or multiple connection bridges 134 may be provided, or no connection bridge 134 may be provided, which is not limited in this application.
  • the number of fractures 133 is greater than the number of connecting bridges 134, and a plurality of connecting bridges 134 are arranged in a plurality of fractures 133 in one-to-one correspondence, and because the quantity of fractures 133 is more, the remaining fractures 133 may not be provided with connecting bridges 134 .
  • the number of fractures 133 is equal to the number of connection bridges 134 , and a plurality of connection bridges 134 are arranged in the plurality of fractures 133 in a one-to-one correspondence.
  • the second signal line 131 can be divided into N+1 transmission line segments 131 a by setting N breaks 133 , where N is an integer greater than or equal to 2.
  • N is an integer greater than or equal to 2.
  • the second signal line 131 can be divided into four transmission line segments 131 a by three openings 133 , and a connection bridge 134 is provided in each of the three openings 133 .
  • 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 .
  • FIG. 19 is a cross-sectional view of another example of the circuit board 100 provided by the embodiment of the present application.
  • FIG. 20 is an exploded view of the circuit board 100 shown in FIG. 19 .
  • the circuit board 100 is a multilayer board with multiple board bodies, and the dielectric substrate 110 is any one of the multiple board bodies.
  • the circuit board 100 may have M board bodies and M+1 conductive pattern layers, two adjacent conductive pattern layers are separated by a board body, where M is an integer greater than or equal to 2. After the metal patterning of the M boards is completed (that is, the conductive pattern layer is provided), the circuit board 100 is formed by stacking and pressing each other.
  • the first conductive pattern layer 120 can be any one of the M+1 conductive pattern layers, for example, it can be a conductive pattern layer located on the top or bottom surface of the circuit board 100, or it can be inside the circuit board 100 A conductive pattern layer located between two boards.
  • the second conductive pattern layer 130 can be any one of the M+1 conductive pattern layers, for example, it can be a conductive pattern layer located on the top or bottom surface of the circuit board 100, or it can be located inside the circuit board 100 A conductive pattern layer between two boards.
  • the one board may be only one board between the first conductive pattern layer 120 and the second conductive pattern layer 130 , and in this case, the one board is the dielectric substrate 110 .
  • the dielectric substrate 110 is one of the multiple boards at this time.
  • 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 a board body.
  • the circuit board 100 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. Separated by a plate body, adjacent conductive pattern layers are electrically connected through metallized via holes 140 .
  • the first conductive pattern layer 120 is located on the top surface of the entire circuit board 100, and the second conductive pattern layer 130 is located on the bottom surface of the entire circuit board 100.
  • the dielectric substrate 110 can be any of the three boards. One, such as the lowermost board in the figure.
  • the third conductive pattern layer 160 may include a coplanar waveguide transmission line structure, and the coplanar waveguide transmission line structure 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 discussed in this application. limited.
  • the fourth conductive pattern layer 170 may include a coplanar waveguide transmission line structure, and the coplanar waveguide transmission line structure 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 discussed in this application. limited.
  • the relevant settings of the above-mentioned connecting bridge 134 can be performed on one or more layers of coplanar waveguide transmission line structure, but it is necessary to keep At least one layer of the waveguide transmission line structure does not have a connecting bridge 134, so that the signal lines in this layer can be kept intact and continuous, ensuring normal transmission of radio frequency signals.
  • signal lines and ground lines between different layers may be electrically connected through metallized via holes 140 .
  • the metallized via hole 140 of the second conductive pattern layer 130 may be a through hole, a blind hole or a buried hole.
  • the through hole, blind hole or buried hole refers to the entire circuit board 100 , and the through hole runs through the bottom surface and the top surface of the entire circuit board 100 .
  • the blind hole penetrates from the bottom surface or the top surface of the circuit board 100 , but does not penetrate the entire circuit board 100 .
  • the buried vias are buried inside the circuit board 100 but not connected to the outer surface.
  • FIG. 21 is a schematic structural diagram of another example of the circuit board 100 provided by 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 perspective of BB in FIG. 21 . Wherein, 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 .
  • the dielectric substrate 110 is further provided with a dielectric slot 150 , and the dielectric slot 150 is located between the transmission line segment 131a and the second ground line 132 .
  • the dielectric slot 150 By setting the dielectric slot 150, part of the dielectric between the transmission line segment 131a and the second ground line 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 electric field can be reduced.
  • the distribution in the medium can further reduce the dielectric loss of the transmission line and improve the transmission quality of the signal.
  • the medium slots 150 need to be set at intervals in a "segmented slotting" manner, that is, between the transmission line segment 131a and the first A dielectric slot 150 is provided between the two ground wires 132, and the dielectric is reserved where the connection bridge 134 needs to be provided, so that the connection bridge 134 can be arranged on the dielectric substrate 110 by printing conductor patterns.
  • the medium slot 150 is a strip-shaped slot, and runs through both sides of the dielectric substrate 110, that is, the medium slot 150 is a through groove penetrating both sides of the dielectric substrate 110, and the medium slot 150 is along the length of the transmission line segment 131a.
  • Direction extension settings Through the above settings, more media can be excavated, and the distribution of the electric field in the media can be reduced as much as possible, so that the dielectric loss of the transmission line can be further reduced, and the transmission quality of the signal can be improved.
  • 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 .
  • the distance between the notch edge of the dielectric slot 150 and each part of the metal pattern of the second conductive pattern layer 130 is 0.05-0.3 mm.
  • the distance between the notch edge of the dielectric slot 150 and the transmission line segment 131a, the second ground line 132 or the connecting bridge 134 is 0.05-0.3 mm.
  • it may be 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, or 0.2 mm.
  • FIG. 25 is a schematic structural diagram of another example of the circuit board 100 provided by 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 viewed from CC in FIG. 25 . Wherein, 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 .
  • a first conductive side wall 151 is provided on the slot wall of the dielectric slot 150 adjacent to the transmission line segment 131a, and the transmission line segment 131a passes through the first conductive side wall 151 and the first conductive side wall 151.
  • the first signal line 121 is electrically connected.
  • a second conductive side wall 152 is provided on the slot wall of the dielectric slot 150 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 passes through the second conductive side wall 152.
  • the sidewall 152 is electrically connected to the first ground wire 122 .
  • the dielectric slot 150 can be opened as large as possible, and the edge of the slot of the dielectric slot 150 can be close to the edge of the metal pattern, so that the area between the second signal line 131 and the second ground line 132, except for a small amount of dielectric in the part covered by the connecting bridge 134, the rest of the dielectric is almost completely removed, and the main component of the electric field is distributed in the air, so the transmission line loss caused by the dielectric can be minimized.
  • 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
  • the first conductive sidewall 151 is electrically connected to the second conductive sidewall 151.
  • the sidewalls 152 are close to each other and facing each other, thereby increasing the facing area of the signal line and the ground line, and the current distribution in the line is more uniform, thereby reducing conductor loss and reducing the impedance of the transmission line.
  • the second conductive sidewall 152 realizes The electrical connection between the ground wires on both sides of the dielectric substrate 110 makes the metallized via hole 140 in the foregoing embodiments can be omitted. This saves production steps 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 realizes the electrical connection of the signal line and the ground line on both sides of the dielectric substrate 110 at the same time.
  • the manufacturing process of setting the first conductive sidewall 151 and the second conductive sidewall 152 in the dielectric slot 150 is basically compatible with the manufacture of existing double-sided or multi-layer boards. There is no need to add additional manufacturing processes, so the implementation cost is close to zero.
  • FIG. 29 is a schematic flow chart of the fabrication process of the metallized sidewall.
  • a substrate that has been provided with a complete metal thin layer (such as a copper foil layer formed by electroplating) on the surface.
  • the substrate can be double-sided (that is, only includes a dielectric substrate) or The multi-layer board (that is, including multiple dielectric substrates) that has completed the inner layer pattern making and lamination.
  • metallization drilling and metallization grooves are performed at preset positions of the substrate by a drill.
  • electroplating is carried out in the completed holes and grooves, so that the thin metal layer is attached to the walls of the holes and grooves.
  • the dotted line in the figure indicates side wall metallization.
  • non-metallized drilling is carried out to remove the plated hole walls at both ends of the metallized tank wall, that is, the aforementioned two first conductive side walls 151 and second conductive side walls 151 electrically isolated from each other are formed. wall 152.
  • the excess metal on the surface of the substrate is finally removed by an etching process to form a metal pattern.
  • the embodiment of the present application also provides an antenna structure.
  • Fig. 30 is a schematic structural diagram of the antenna structure provided by the present application.
  • the antenna structure provided by the embodiment of the present application includes an antenna unit 200 and a circuit board 100 provided in any of the foregoing embodiments.
  • the antenna structure is a directional antenna, and the antenna unit 200 is arranged on one side of the circuit board 100 .
  • the circuit board 100 constitutes a reflection plate of the antenna unit 200 .
  • the antenna structure may be an active antenna or a passive antenna.
  • the antenna unit 200 may be a dipole antenna.
  • multiple antenna units 200 may be included and arranged on the circuit board 100 in an array.
  • the antenna unit 200 is electrically connected to the circuit board 100 , for example, the transmission line structure on the circuit board 100 may serve as a feeder for the antenna unit 200 .
  • circuit board 100 ensures the integrity and sealing of the ground plane (or in other words, does not destroy the integrity of the ground plane), it can reduce the electromagnetic radiation interference generated by the circuit board 100 to external components, so the circuit board 100 can be used as a reflector for a directional antenna without affecting the pattern performance of the antenna.
  • a specific simulation example is described below.
  • the antenna unit 200 is a dipole antenna
  • the circuit board 100 shown in the foregoing Figures 25-28 is used as the reflector of the antenna unit 200
  • the length of the transmission line is 150 millimeters, using the same simulation as in the foregoing Figure 10
  • the only difference is that the conventional double-layer coplanar waveguide transmission line structure is replaced by the double-layer coplanar waveguide transmission line structure with the connecting bridge 134 provided by the embodiment of the present application.
  • Fig. 31 is a radiation pattern diagram of the antenna structure provided by the embodiment of the present application. Comparing Figure 21 with the aforementioned Figure 6, it can be seen that the antenna pattern does not deteriorate significantly, because the setting of the connecting bridge 134 avoids the occurrence of long slots on the ground plane and ensures the sealing of the ground plane and integrity.
  • the antenna structure adopts the circuit board 100 provided in the above-mentioned embodiments, the antenna structure also has the technical effect corresponding to that of the circuit board 100 , which will not be repeated here.
  • the embodiment of the present application also provides an electronic device, the electronic device includes a casing and the circuit board 100 provided in any one of the foregoing embodiments, and the circuit board 100 is located in the casing.
  • the electronic device may be a handheld device, vehicular device, wearable device, computing device, or other processing device connected to a wireless modem.
  • the electronic device may be a mobile phone, a tablet computer, a laptop computer, a smart watch, a smart bracelet, smart glasses, or a smart TV (smart screen).
  • the electronic device may be a communication device, such as a base station or a radar.
  • the electronic device further includes the aforementioned antenna unit 200 , the antenna unit 200 is disposed on one side of the circuit board 100 , and the circuit board 100 constitutes a reflector of the antenna unit 200 . That is to say, the electronic device may further include the antenna structure provided in the foregoing embodiments, and the antenna structure is disposed in the casing.
  • the electronic device adopts the circuit board 100 provided in the above embodiment, the electronic device also has the technical effect corresponding to that of the circuit board 100 , which will not be repeated here.

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Abstract

本申请提供了一种电路板、天线结构及电子设备，该电路板包括：介质基板；第一导电图形层，设于介质基板的一侧，第一导电图形层包括第一信号线；第二导电图形层，设于介质基板的另一侧，第二导电图形层包括第二信号线以及间隔设置于第二信号线两侧的两个第二地线；第二信号线包括排成一列的多个传输线段，相邻两个传输线段之间具有断口，第二导电图形层还包括与第二信号线电隔离的连接桥，连接桥位于断口内并且电气连接两个第二地线，每个传输线段与第一信号线电连接。本申请通过对电路板上的共面波导的结构进行改进，保证了地平面的完整性和封闭性，由此提高了电路板的抗干扰性能，并且降低了电路板对外部元器件产生的电磁辐射。

Description

电路板、天线结构及电子设备
本申请要求于2021年08月13日提交国家知识产权局、申请号为202110935457.1、申请名称为“电路板、天线结构及电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，并且更具体地，涉及一种电路板、天线结构及电子设备。
背景技术
电路板是电子元件进行电气连接的基本载体，其主要功能是支撑电子元件以及互连电子元件。在现代通信电路设计中，通常通过传输线来实现电路板上不同电子元件之间的信号传输。传输线是一种输送电磁能的线状结构，它是电信系统的重要组成部分，用来把载有信息的射频信号从一点传送到另一点。在电子设备中，常用的传输线包括微带线、带状线、单层共面波导、双层共面波导等结构。
双层共面波导是一种常用的传输线结构，相比于微带线或者带状线等传输线结构，双层共面波导能够减小电场在介质基板中的分布，进而能够一定程度的抑制介质损耗的问题。但是由于此时电路板的地平面由共面波导的两个地线和信号线共同构成，由于信号线和两侧的地线之间均具有长度很大的开槽(间隙)，由此破坏了电路板地平面的完整性，导致电路板的封闭性较差，对电磁波的屏蔽性能也较差。以上原因使得电路板上的电磁元件容易与外部元器件产生电磁波“耦合”，造成电路板自身的抗干扰性能较差，并且也容易对外部元器件产生辐射干扰。
发明内容
本申请提供一种电路板、天线结构及电子设备，通过对电路板上的共面波导的结构进行改进，减小了地平面上开槽的长度，保证了地平面的完整性和封闭性，由此提高了电路板的抗干扰性能，并且降低了电路板对外部元器件产生的电磁辐射。
第一方面，提供了一种电路板，包括：介质基板，由绝缘材料构成；第一导电图形层，设于所述介质基板的一侧，所述第一导电图形层包括第一信号线；第二导电图形层，设于所述介质基板的另一侧，所述第二导电图形层包括第二信号线以及间隔设置于所述第二信号线两侧的两个第二地线；所述第二信号线包括排成一列的多个传输线段，相邻两个所述传输线段之间具有断口，所述第二导电图形层还包括与所述第二信号线电隔离的连接桥，所述连接桥位于所述断口内并且电气连接两个所述第二地线，每个所述传输线段与所述第一信号线电连接。
根据本申请实施例提供的电路板，第二导电图形层包括共同构成共面波导传输线结构的第二信号线和两个第二地线，该共面波导传输线结构能够构成电路板的地平面。第二信号线被截断为多个传输线段，相邻两个传输线段之间均具有断口，在该断口内，设置有连接两侧第二地线的连接桥。本申请通过设置连接桥能够减小第二信号线和第二地线之间开槽的长度，增大了导电图形在介质基板上的设置面积(即增大了地平面的覆盖面积)，提高了地平面的完整性和封闭性，进而提高了地平面对电磁波的屏蔽性能。此时，在该地平 面的高效隔绝作用下，电路板上的电磁元件不易与外部元器件产生电磁波“耦合”，由此提高了电路板的抗干扰性能，并且降低了电路板对外部元器件产生的电磁辐射影响。
本申请实施例中的第二导电图形层可以通过平面印刷等工艺集成于介质基板之上，保持了传统的共面波导传输线尺寸小型化、易与芯片集成等优势。连接桥的设置的不需增加额外工序，具备接近于零的实施成本。以上原因使得本申请实施例提供的电路板具有尺寸小、集成度高、成本低等优势，在电子产品中具备广泛的应用空间。
本申请实施例提供的电路板采用共面波导传输线结构进行射频信号的传输，相比于微带线或者带状线等传输线结构，能够使得主要电场分布在空气中，由此减小了电场在介质基板中的分布，能够一定程度的抑制介质损耗的问题，进而能够实现射频信号的低损耗传输，提高了信号传输的质量。此外，由于信号电场主要分布在空气中，单位长度延时小，能够减小相位绕线，实现信号的低延时传输。
可选地，电路板包括但不限于：底板、中板、背板、柔性电路板、刚性电路板、软硬结合板、终端电路板、封装载板、低温共烧陶瓷基板或高温共烧陶瓷基板等。封装载板可以是系统级封装载板、单芯片封装载板多芯片封装载板或球栅阵列封装载板等。
当电路板为刚性电路板时，介质基板由硬质绝缘材料构成。可选地，构成介质基板的材质可以为陶瓷材料、树脂材料、玻璃材料或者硬塑料等中的至少一种材料构成。
例如，介质基板可以由氧化铝陶瓷、氮化铝陶瓷、酚醛树脂、环氧树脂、溴化环氧树脂、聚脂或者聚四氟乙烯等中的至少一种材料构成。
当电路板为柔性电路板时，介质基板由柔性绝缘材料构成。例如，介质基板可以由聚酯、聚酰亚胺、氟碳或芳香族聚酰胺等中的至少一种材料构成。此时电路板可应用于可折叠电子设备(例如可折叠手机)中。
在一种可能的设计中，所述连接桥与所述断口均为多个，每个所述连接桥均位于所述断口内。通过以上设置，能够在信号传输距离较长的情况下，因地制宜的设置更多个连接桥，确保传输线段不会太长，即确保传输线段与第二地线之间的开槽长度不会过大，由此保证了地平面的完整性和封闭性，即确保了地平面能够具有良好的屏蔽性能。此外，开槽长度过大不利于生产加工(铣刀切割路径太长容易出现误差)，本申请通过设置多个连接桥134来缩短开槽的长度，能够提高生产的效率，降低生产成本。
可选地，断口的数量可以大于、等于或者小于连接桥的数量。
可选地，不同断口内设置的连接桥的数量可以相同或者不同。
可选地，断口内可以仅设置一个连接桥，或者设置多个连接桥，或者不设置连接桥，本申请对此不做限定。
例如，断口的数量大于连接桥的数量，多个连接桥一一对应的设置于多个断口内，而由于断口的数量更多，剩余的断口内可以不设置连接桥。
在一种可能的设计中，所述连接桥与所述断口的数量相等，多个所述连接桥与多个所述断口一一对应。通过以上设置，能够尽可能的增大导电图形在介质基板上的覆盖面积，即增大地平面的面积，保证地平面的完整性和封闭性。此外还有利于简化加工程序，降低生产成本。
在一种可能的设计中，所述传输线段的长度小于所述第二信号线所传输电磁波信号的0.5倍波长。通过以上设置，能够避免传输线段在其他电磁波信号的作用下发生谐振，进 而能够确保第二信号线传输的稳定性。此外，以上设置也可以作为一个将第二信号线分割成多少个传输线段的参考依据。
在一种可能的设计中，每个传输线段通过金属化过孔与所述第一信号线电连接。
在一种可能的设计中，所述第一导电图形层还包括间隔设置于所述第一信号线两侧的两个第一地线，所述第二地线与所述第一地线电连接。
在一种可能的设计中，所述介质基板上还设有介质开槽，所述介质开槽位于所述传输线段与所述第二地线之间。通过设置介质开槽，能够将位于传输线段与第二地线之间的部分介质挖除，由此使得传输线段产生的电场能够更多的分布于空气中，而减小电场在介质中的分布，进而能够进一步降低传输线的介质损耗，提高信号的传输质量。在一种可能的设计中，所述介质开槽为条形槽，并贯穿所述介质基板的两侧(即此时介质开槽为通槽)，所述介质开槽沿着所述传输线段的长度方向延伸设置。通过以上设置，能够挖除更多的介质，尽可能的减小电场在介质中的分布，进而能够进一步降低传输线的介质损耗，提高信号的传输质量。
可选地，在其他实施方式中，介质开槽也可以为盲槽，此时介质开槽并未贯穿介质基板的两侧。
在一种可能的设计中，所述介质开槽的槽口边缘与所述传输线段、所述第二地线或者所述连接桥之间的距离为0.05～0.3毫米。
例如，可以为0.08毫米、0.1毫米、0.12毫米、0.15毫米或者0.2毫米等。
通过在槽口和金属图形之间设置一定的安全距离，能够在开槽制作的过程中，避免铣刀损伤金属图形(例如铜箔)边沿，形成金属毛刺和裸露铜箔，影响传输线抗腐蚀、抗氧化等方面的性能。
在一种可能的设计中，所述介质开槽邻近所述传输线段一侧的槽壁上设有第一导电侧壁，所述传输线段通过所述第一导电侧壁与所述第一信号线电连接；所述介质开槽邻近所述第二地线一侧的槽壁上设有第二导电侧壁，所述第二导电侧壁与所述第一导电侧壁电隔离，所述第二地线通过所述第二导电侧壁与所述第一地线电连接。
通过以上设置，一方面，能够使得介质开槽开设的尽量大，介质开槽的槽口边缘可以靠近金属图形的边沿，使得第二信号线与第二地线之间的区域，除连接桥覆盖的部分保留有少量介质外，其余部分的介质几乎全部被去除，电场主要分量分布在空气中，因此能够最大程度降低介质引起的传输线损耗。
另一方面，第一导电侧壁与双层共面波导的信号线电连接，第二导电侧壁双层共面波导的地线电连接，而第一导电侧壁与第二导电侧壁相互靠近且正对，由此能够增大信号线与地线的正对面积，线内的电流分布也更加均匀，由此减小了导体损耗，并降低了传输线的阻抗。
在一种可能的设计中，所述第二地线通过金属化过孔与所述第一地线电连接。
在一种可能的设计中，所述电路板为双面板。
在一种可能的设计中，所述电路板为具有多个板体的多层板，所述介质基板为所述多个板体中的任意一个。
可选地，第一导电图形层和第二导电图形层之间可以仅具有一个板体，此时该一个板体即介质基板。
可选地，第一导电图形层和第二导电图形层之间也可以具有多个板体，此时介质基板为该多个板体中的一个。
在一种可能的设计中，所述金属化过孔为通孔、盲孔或者埋孔。
在一种可能的设计中，所述第二导电图形层为由蚀刻工艺制成的金属层。
第二方面，还提供了一种天线结构，包括天线单元以及前述第一方面中任一种可能设计所提供的电路板，所述天线单元设于所述电路板的一侧，所述电路板构成所述天线单元的反射板。
由于第一方面提供的电路板保证了地平面的完整性和封闭性(或者说，没有破坏地平面的完整性)，能够降低电路板对外部元器件产生的电磁辐射干扰，因此电路板能够作为定向天线的反射板使用，而不会影响天线的方向图性能。
可选地，该天线结构可以是有源天线或者无源天线。
可选地，天线单元可以为偶极子天线。
可选地，天线单元可以包括多个，并且以阵列的形式排布于电路板之上。
可选地，天线单元与电路板电气连接，例如电路板上的传输线结构可以作为天线单元的馈线。
第三方面，提供了一种电子设备，包括壳体以及前述第一方面中任一种可能设计所提供的电路板，所述电路板位于所述壳体内。
可选地，该电子设备可以是手持设备、车载设备、可穿戴设备、计算设备或连接到无线调制解调器的其它处理设备。
例如，该电子设备可以是手机、平板电脑、笔记本电脑、智能手表、智能手环、智能眼镜或者智能电视(智慧屏)等。
可选地，该电子设备可以是通信设备，例如可以是基站或者雷达。
在一种可能的设计中，所述电子设备还包括位于所述壳体内的天线单元，所述天线单元设于所述电路板的一侧，所述电路板构成所述天线单元的反射板。
附图说明
图1示出了各种不同类型的传输线的结构示意图。
图2示出了微带线在信号传输过程中造成损耗的原理示意图。
图3是悬置带状线和悬置微带线的结构示意图。
图4是通过共面波导来降低介质损耗的原理示意图。
图5示出了三种常用的共面波导传输线结构。
图6是电路板未设置传输线的天线结构的结构示意图。
图7是图6所示的天线结构的辐射方向图。
图8是电路板设置微带线的天线结构的结构示意图。
图9是图8所示的天线结构的辐射方向图。
图10是电路板设置双层共面波导的天线结构的结构示意图。
图11是图10所示的天线结构的辐射方向图。
图12是本申请实施例提供的电路板的结构示意图。
图13是图12所示的电路板的爆炸图。
图14是图12所示的电路板的俯视图和仰视图。
图15是图12中AA视角的剖视图。
图16是本申请实施例提供的电路板的另一例的结构示意图。
图17是图16所示的电路板的爆炸图。
图18是图16所示的电路板的俯视图和仰视图。
图19是本申请实施例提供的电路板的再一例的剖视图。
图20是图19所示的电路板的爆炸图。
图21是本申请实施例提供的电路板的再一例的结构示意图。
图22是图21所示的电路板的爆炸图。
图23是图21所示的电路板的俯视图和仰视图。
图24是图21中BB视角的剖视图。
图25是本申请实施例提供的电路板的再一例的结构示意图。
图26是图25所示的电路板的爆炸图。
图27是图25所示的电路板的俯视图和仰视图。
图28是图25中CC视角的剖视图。
图29是金属化侧壁制作过程的流程示意图。
图30是本申请提供的天线结构的结构示意图。
图31是本申请实施例提供的天线结构的辐射方向图。
附图标记：
11、介质基板；12、信号线；13、接地面；14、地线；15、金属化过孔；
21、介质基板；22、参考地平面；23、微带线；2H、磁场；2E、电场；
31、金属板；32、金属侧壁；33、空腔；34、金属信号线；35、间隙；
41、介质基板；42、信号线；43、地线；44、接地面；45、金属化过孔；4E、电场；
51、介质基板；52、偶极子天线；53、微带线；54、共面波导；55、金属化过孔；
100、电路板；110、介质基板；120、第一导电图形层；121、第一信号线；122、第一地线；130、第二导电图形层；131、第二信号线；131a、传输线段；132、第二地线；133、断口；134、连接桥；140、金属化过孔；150、介质开槽；151、第一导电侧壁；152、第二导电侧壁；160、第三导电图形层；170、第四导电图形层。
具体实施方式
下面详细描述本申请的实施方式，所述实施方式的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施方式是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。
在本申请的描述中，需要理解的是，术语“第一”、“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”等的特征可以明示或者隐含地包括一个或者更多个所述特征。在本申请的描述中，“多个”的含义是两个或两个以上，除非另有明确具体的限定。
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以 是机械连接，也可以是电连接或可以相互通讯；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
在本申请的描述中，需要理解的是，术语“上”、“下”、“侧”、“前”、“后”、“内”、“外”等指示的方位或位置关系为基于安装的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。
还需说明的是，本申请实施例中以同一附图标记表示同一组成部分或同一零部件，对于本申请实施例中相同的零部件，图中可能仅以其中一个零件或部件为例标注了附图标记，应理解的是，对于其他相同的零件或部件，附图标记同样适用。
电路板是电子元件进行电气连接的基本载体，其主要功能是支撑电子元件以及互连电子元件。电路板使电路迷你化、直观化，对于电路的批量生产和优化布局起重要作用。按照电路层数进行划分，电路板通常包括单面板、双面板和多层板。
其中，单面板是最基本的电路板，元器件集中在介质基板的一面上，导线则集中在介质基板的另一面。双面板是介质基板的双面都进行布线(敷铜)的电路板。此时，介质基板两面的导线构成导电图形层，介质基板构成介于两个导电图形层之间的绝缘层。多层电路板包括多个导电图形层(3层及3层以上)和多个绝缘层(即包括多个介质基板)，相邻的两个导电图形层均以绝缘层隔开，且相邻两个导电图形层通过导电过孔(又叫金属化过孔)电连接。
在现代通信电路设计中，通常通过传输线(transmission line)来实现电路板上不同电子元件之间的信号传输。传输线是一种输送电磁能的线状结构，它是电信系统的重要组成部分，用来把载有信息的电磁波(射频信号)沿着传输线规定的路由自一点输送到另一点。在电子设备中，常用的传输线包括微带线(microstrip)、带状线(stripline)、共面波导(coplanar waveGuide，CPW)、接地共面波导(grounded coplanar waveGuide，GCPW)、衬底集成波导(substrate integrated waveguide，SIW)、同轴电缆、波导、双绞线等结构。
图1示出了各种不同类型的传输线的结构示意图。如图1中的(a)部分所示，微带线为形成于介质基板11顶面的呈带状的信号线12，该信号线12由金属材料(例如铜)构成，能够用于传播射频信号，介质基板11由绝缘介质构成，能够起到电气隔绝的作用，在介质基板11的底面设有接地面13。这里的接地面通常也被称作参考地、参考地平面或地平面等，通常为电镀上去的铜箔(铜皮)。
如图1中的(c)部分所示，带状线为介于两个介质基板11的贴合面之间的呈带状的信号线12，两个介质基板11相互背离的表面分别各自设置有接地面13，进而使得信号线12介于两个接地面13之间，介质基板11上开设有金属化过孔15，两侧的两个接地面13通过金属化过孔15进行电连接，能够保证两个接地面13的电位相等。其中，通过在介质基板11上开设连通两侧的通孔，并且在通孔内设置金属导电材料以形成该金属化过孔15，该金属导电材料两端分别与两侧的接地面13电连接。
如图1中的(d)部分所示，共面波导又叫共面微带传输线，包括形成于介质基板11顶面的3根带状导线，3根带状导线彼此之间相互平行，并且间隔设置。其中，位于中间的带状导线构成传输信号的信号线12，两侧的两个带状导线构成两根地线14。根据实际 需求，地线14可以设计的尽量宽一些，以使得两根地线14和信号线12共同构成具有沟槽(信号线12与地线14之间的间隙)的“地平面”。该地平面可以作为天线的反射面。
如图1中的(b)部分所示，接地共面波导又叫背敷金属共面波导，在图1中(d)部分所示的共面波导的基础上，在介质基板11的地面还设置有接地面13，接地面13通过金属化过孔15与另一侧的地线14保持电连接。相比于图1中(d)部分所示的共面波导，接地面13的设置，不仅加强了介质基板11的机械强度，更为有源器件提供了良好的散热介质。
如图1中的(a)-(d)部分所示，在以上传输线结构中，微带线、带状线、GCPW、CPW这几类传输线具有结构紧凑、集成度高的特点，并且便于采用平面印刷工艺制作，因此一般应用于印刷电路板(printed circuit board，PCB)、芯片、封装基板等平面电路中。这类传输线易与电路集成，但一般损耗较大。图1中的(e)、(f)、(g)部分分别为波导、双绞线以及同轴电缆的结构示意图。波导、双绞线以及同轴电缆等传输线结构一般应用于设备到设备或模块到模块之间的信号连接，这类传输线损耗小，但是体积大不便于与电路集成。
虽然微带线、带状线、GCPW、CPW这几类传输线具有尺寸小、集成度高、便于与芯片或电路集成等优势，但也存在很大的不足，就是损耗较大，特别是在传输高频信号的情况下，损耗成为制约这类传输线应用的关键问题。
造成损耗的主要原因在于这几类传输线结构导体都是印刷附着在介质基板上，在信号传输过程中，大部分电场分布在介质基板中，由于构成介质基板的绝缘介质的分子会在交变电场的作用下产生振动，将部分电磁能转化为热能，从而导致传输线输出点的信号能量减少，形成介质损耗(即由于介质基板的绝缘介质引起的损耗)。
下面结合一个具体示例对介质损耗进行说明。图2示出了微带线在信号传输过程中造成损耗的原理示意图。如图2所示，介质基板21的顶面设置有微带线23，底面设置有参考地平面22。在微带线23上电工作的状态下，例如在传输高频信号时，微带线23的周侧形成电场2E(图2中实线箭头部分)和磁场2H(图2中虚线部分)，由图2可知，电场2E的方向从微带线23穿过中间的介质基板21射向另一侧的参考地平面22，由此使得电场2E大部分分布于介质基板21中，构成介质基板21介质分子在交变电场的作用下产生振动，将部分电磁能转化为热能，从而导致微带线23输出点的信号能量减少，形成介质损耗。
由介质引起的损耗一方面与材料的特性有关，由材料的微观分子结构确定；另一方面与所传输信号的频率有关，频率越高，损耗则越大。当前，通常从改进介质基板的材料特性、减少电场在介质基板中的分布以及采用共面波导结构这三个方面来减小介质损耗。下面对这三种方式分别进行介绍。
1、通过改进介质基板的材料特性来降低介质损耗。
为了减小介质引起的损耗，首先可以采用的方法就是改进构成介质基板的材料的特性，目前市面上许多厂家都推出了针对高频信号应用的系列化PCB板材产品，这些产品通过改变材料的微观分子结构实现介质损耗的降低。
然而，但这类材料通常都存在3个方面的问题：①材料成本高，研发新型材料需要投入大量的人力物力。②介质损耗以外的其它性能出现恶化，导致应用成本上升，比如材料 的温度稳定性、阻燃、抗腐蚀等其它方面性能出现恶化。③损耗性能仍然难以达到电路系统需求，尽管材料的配方改进可以在较大程度上降低介质损耗，但是无法无限降低，达到接近空气的程度。以上原因使得通过改进材料的特性这一方式来降低介质损耗不太可行。
2、通过减少电场在介质基板中的分布来降低介质损耗。
另一个降低介质损耗的方法就是尽量减少电场在介质中的分布，其中应用较多的是悬置线结构，包括悬置带状线和悬置微带线等，其基本结构如图3所示。图3是悬置带状线和悬置微带线的结构示意图，其中，图3中的(a)部分示出了悬置带状线的基本结构，图3中的(b)部分示出了悬置微带线的基本结构。
如图3中的(a)部分所示，悬置带状线结构包括相对间隔设置的两个金属板31、位于两个金属板31之间并且间隔设置的两个金属侧壁32，两个金属板31和两个金属侧壁32共同围成空腔33，金属信号线34被悬置于空腔33内。如图3中的(b)部分所示，悬置微带线结构包括金属板31，金属信号线34被悬置于金属板31上方，在金属板31与金属信号线34之间具有间隙35。通过将金属信号线34悬置，能够使得金属信号线34与介质基板相互分离(中间形成空气层)，由于金属信号线34与介质基板具有一定的距离，使得金属信号线34形成的电场大多分布于空气中，而尽量减少电场在介质中的分布。
悬置线结构虽然实现了降低介质损耗的目的，但是由于信号线和地平面分离，不是印刷附着在同一介质基板上，导致了结构复杂性的增加，需要添加额外的反射板和支撑部件，集成度也很大程度降低，成本也大幅上升。例如专利公开号为CN106785284A的现有技术公开了一种通过多层PCB叠置形成的悬置带状线结构，该结构通过5层PCB实现了带状线的悬置，成本相对普通双面PCB上升5倍以上，厚度增加2倍以上。
相对而言，图3中的(a)部分示出的悬置微带线结构简单一些，但是为了实现信号导体悬空，也需要复杂的支撑结构，同时为了降低制造难度，减小组装误差对悬置微带线阻抗的影响，一般会将金属信号线34与金属板31设置较远的距离，这也导致悬置微带线封闭性不良，容易出现对外辐射(形成对外干扰并增加损耗)，临近线间耦合等问题。
3、通过采用共面波导结构来降低介质损耗。
另一种减少电场在介质基板中分布的传输线结构为共面波导。图4是通过共面波导来降低介质损耗的原理示意图。如图4所示，介质基板41的一面通过印刷等工艺设置有共面波导，该共面波导包括信号线42，以及并列设置于信号线42相对两侧的两根地线43，地线43与信号线42相互间隔开。
在信号线42上电工作的状态下，信号线42的周侧形成电场4E(图4中实线箭头部分)。由图2可知，电场4E的方向从信号线42穿过信号线42与地线43之间形成的间隙(开槽)后射向地线43，而非垂直于介质基板41，使得一部分电场4E位于介质基板41内，而另一部分分布于空气中，由此减小了电场4E在介质基板41中的分布，介质分子的振动被抑制，由此降低了介质损耗。
图5示出了三种常用的共面波导传输线结构。其中，图5中的(a)部分为单层共面波导传输线结构的剖面图。图5中的(b)部分为单层带参考地的共面波导传输线结构的剖面图。图5中的(c)部分为双层共面波导传输线结构的剖面图。
如图5中的(a)部分所示，通过采用单层共面波导来降低介质损耗是最常用的方式之一。然而，单层共面波导虽然一定程度上减少了电场在介质中的分布，但由于信号线 42和地线43之间正对面积很小，导致传输线阻抗较高，另外受趋肤效应影响，电流分布集中在微带线的边沿，由于电流分布区域小导致导体损耗加大，因此在实际电子产品中使用不多。
如图5中的(b)部分所示，对于单层带参考地的共面波导传输线结构，共面波导和接地面44设置于介质基板41相对的两个侧面上，使得该结构类似微带线，电场仍然大部分分布在介质内，对改善损耗没有作用，其作用是可以增强微带线和临近其他传输线的隔离。
如图5中的(c)部分所示，对于双层共面波导传输线结构，两个共面波导分别设置于介质基板41相对的两个侧面上，并且通过多个金属化过孔45实现两侧的信号线42之间的电连接，以及实现两侧的地线43之间的电连接。
通常在高频电子产品的电路板设计中都需要完整的地平面，否则会造成电路板的抗干扰性能降低和对外干扰辐射增加等问题。双层共面波导传输线结构在实际电子产品中使用也不多，其问题在于此时电路板的地平面由共面波导的两个地线43和信号线42共同构成，信号线42和两侧的地线43之间均具有长度很大的开槽，由此破坏了电路板地平面的完整性，导致电路板的封闭性较差，对电磁波的屏蔽性能也较差。电路板上的共面波导等电磁元件产生的电磁波容易通过开槽射向电路板外部对其他元器件造成电磁干扰，并且其他元器件产生的电磁波也容易通过开槽对电路板上的电磁元件造成影响。下面将进一步通过具体的仿真实例来说明双层共面波导传输线结构存在的上述问题。
图6是电路板未设置传输线的天线结构的结构示意图。图7是图6所示的天线结构的辐射方向图。如图6所示的仿真场景，该天线结构包括一块180*180mm电路板，其上设置有一工作频率为1.7GHz～2.7GHz的偶极子天线52，该电路板构成偶极子天线52的反射板，该电路板包括介质基板51，介质基板51的底面(即背离偶极子天线52的一面)覆盖铜箔，电路板上的铜箔作为偶极子天线52的反射面，与偶极子天线52一起构成一个具有定向辐射功能的天线，其辐射方向图如图7所示。
图8是电路板设置微带线的天线结构的结构示意图。图9是图8所示的天线结构的辐射方向图。如图8所示，在图6所示场景的基础上，作为另一仿真实例，在介质基板51的正面(即朝向偶极子天线52的一面)设置一段长度为150mm的微带线53，此时天线结构的辐射方向图如图9所示。对比图7和图9可以看出，微带线52的添加并没有引起天线方向图出现恶化，这是因为介质基板51背面的铜箔没有被破坏，偶极子天线53的反射面仍然完整。
图10是电路板设置双层共面波导的天线结构的结构示意图。图11是图10所示的天线结构的辐射方向图。如图10所示，在图6所示场景的基础上，作为再一仿真实例，在介质基板51的两个侧面各自设置一个共面波导54，并且通过多个金属化过孔55实现两侧的信号线之间的电连接，以及实现两侧的地线之间的电连接。共面波导54的长度为150mm，此时天线的方向图如图11所示。对比图7和图11可知，此时天线结构的辐射方向图出现了非常严重的恶化，这是由于双层共面波导走线的引入使地平面上出现的长度很大的开槽(信号线和两侧的地线之间各自形成一个开槽)，由此破坏了地平面的完整性，使得电路板对偶极子天线52产生较强的辐射干扰。
综上所述，相比于微带线或者带状线等传输线结构，双层共面波导能够减小电场在介 质基板中的分布，进而能够一定程度的抑制介质损耗的问题。但是由于此时电路板的地平面由共面波导的两个地线和信号线共同构成，由于信号线和两侧的地线之间均具有长度很大的开槽，由此破坏了电路板地平面的完整性，导致电路板的封闭性较差，对电磁波的屏蔽性能也较差。
此时电路板上的共面波导等电磁元件产生的电磁波容易通过开槽射向电路板外部对其他元器件造成干扰，并且其他元器件产生的电磁波也容易通过开槽对电路板上的电磁元件造成影响。也就是说，当前的双层共面波导传输线结构容易使得电路板上的电磁元件与外部元器件产生电磁波“耦合”，造成电路板自身的抗干扰性能较差，并且也容易对外部元器件产生辐射干扰。
有鉴于此，本申请实施例提供了一种电路板、天线结构及电子设备，通过对电路板上的共面波导结构进行改进，减小了地平面上开槽的长度，提高了地平面的完整性和封闭性，由此提高了电路板的抗干扰性能，并且降低了电路板对外部元器件产生的电磁辐射。
第一方面，本申请实施例首先提供了一种电路板100。图12是本申请实施例提供的电路板100的结构示意图。图13是图12所示的电路板100的爆炸图。图14是图12所示的电路板100的俯视图和仰视图。图15是图12中AA视角的剖视图。如图12-图15所示，本申请实施例提供的电路板100包括介质基板110、第一导电图形层120以及第二导电图形层130。
其中，介质基板110由绝缘材料构成，并且位于第一导电图形层120和第二导电图形层130之间，以对上述两个导电层进行电气隔绝。第一导电图形层120以图形化的方式设于介质基板110的一侧，第一导电图形层120包括第一信号线121。第一信号线121用于传输射频信号，第一信号线121可以为具有一定宽度的金属带状(条带)线。
第二导电图形层130以图形化的方式设于介质基板110的另一侧，第二导电图形层130包括第二信号线131以及间隔设置于第二信号线131两侧的两个第二地线132。并列且间隔设置的第二信号线131和两个第二地线132共同构成了共面波导传输线结构。第二信号线131以及两个第二地线132均为具有一定宽度的金属带状线。
图14中的(a)部分为电路板100的俯视图，图14中的(b)部分为电路板100的仰视图。如图13以及图14中的(b)部分所示，第二信号线131包括排成一列的多个传输线段131a(例如图中的两个)，相邻两个传输线段131a之间具有断口(缺口)133。换句话说，断口133将第二信号线131分割成多个传输线段131a。第二导电图形层130还包括与第二信号线131电隔离的连接桥134，连接桥134位于断口133内并且电气连接两个第二地线132。也就是说，断口133的设置能够供连接桥134穿过，并且断口133的宽度大于连接桥134的宽度，以使得连接桥134能够与断口133两侧的两个传输线段131a电气隔离。
进一步地，如图13、图15所示，介质基板110上还设置有金属化过孔140，该金属化过孔140通过在介质基板110上开设连通两侧的通孔，并且在该通孔内(例如孔壁上)设置金属导电材料而形成。多个传输线段131a中的每一个至少通过一个金属化过孔140与介质基板110另一侧的第一信号线121电连接，第一信号线121通过金属化过孔140将射频信号传输至每一个传输线段131a。
根据本申请实施例提供的电路板100，第二导电图形层130包括共同构成共面波导传 输线结构的第二信号线131和两个第二地线132，该共面波导传输线结构能够构成电路板100的地平面。第二信号线131被截断为多个传输线段131a，相邻两个传输线段131a之间均具有断口133，在该断口133内，设置有连接两侧第二地线132的连接桥134。本申请通过设置连接桥134能够减小第二信号线131和第二地线132之间开槽的长度，增大了导电图形在介质基板110上的设置面积(即增大了地平面的覆盖面积)，提高了地平面的完整性和封闭性，进而提高了地平面对电磁波的屏蔽性能。此时，在该地平面的高效隔绝作用下，电路板上的电磁元件不易与外部元器件产生电磁波“耦合”，由此提高了电路板的抗干扰性能，并且降低了电路板对外部元器件产生的电磁辐射影响。
本申请实施例中的第二导电图形层130可以通过平面印刷等工艺集成于介质基板110之上，保持了传统的共面波导传输线尺寸小型化、易与芯片集成等优势。连接桥134的设置的不需增加额外工序，具备接近于零的实施成本。以上原因使得本申请实施例提供的电路板100具有尺寸小、集成度高、成本低等优势，在电子产品中具备广泛的应用空间。
本申请实施例提供的电路板100采用共面波导传输线结构进行射频信号的传输，相比于微带线或者带状线等传输线结构，能够使得主要电场分布在空气中，由此减小了电场在介质基板110中的分布，能够一定程度的抑制介质损耗的问题，进而能够实现射频信号的低损耗传输，提高了信号传输的质量。此外，由于信号电场主要分布在空气中，单位长度延时小，能够减小相位绕线，实现信号的低延时传输。
下面结合附图对本申请实施例提供的电路板100做进一步介绍。本申请实施例提供的电路板100能够用于传输高速信号，电路板100包括但不限于：底板、中板、背板、柔性电路板(flexible printed circuit board，FPC)、刚性电路板、软硬结合板、终端电路板、封装载板、低温共烧陶瓷(low-temperature cofired ceramics，LTCC)基板或高温共烧陶瓷(high-temperature co-fired ceramics，HTCC)基板等。封装载板可以是系统级封装(system in package，SIP)载板、单芯片封装(single chip package，SCP)载板多芯片封装(multi chip package，MCP)载板或球栅阵列(ball grid array，BGA)封装载板等。
当电路板100为刚性电路板时，介质基板110由硬质绝缘材料构成。可选地，构成介质基板110的材质可以为陶瓷材料、树脂材料、玻璃材料或者硬塑料等中的至少一种材料构成。
例如，介质基板110可以由氧化铝陶瓷、氮化铝陶瓷、酚醛树脂、环氧树脂、溴化环氧树脂、聚脂或者聚四氟乙烯等中的至少一种材料构成。
当电路板100为柔性电路板时，介质基板110由柔性绝缘材料构成。例如，介质基板110可以由聚酯、聚酰亚胺、氟碳或芳香族聚酰胺等中的至少一种材料构成。此时电路板100可应用于可折叠电子设备(例如可折叠手机)中。
可选地，电路板100可以为双面板，也可以为多层板，本申请对此不做限定。在本申请实施例中，如图12-图15所示，电路板100为双面板，此时电路板100仅包括一个板体，即介质基板110，此时第一导电图形层120和第二导电图形层130分别设置于介质基板110相对的两个侧面上。
可选地，在其他实施方式中，电路板100也可以为多层板，此时电路板100包括相互层叠设置的多个板体，相邻板体之间具有导电层，介质基板110为该多个板体中的任意一个。此时，第一导电图形层120和第二导电图形层130设置于介质基板110相对的两侧， 可以直接设置于介质基板110之上，也可以通过中间媒介(例如至少一个板体和/或导电层)与介质基板110相连接。
如图12-图15所示，介质基板110的顶面(上表面)设置有第一导电图形层120，介质基板110的底面(下表面)设置有第二导电图形层130。可以通过印刷、蚀刻或其它工艺在介质基板110的表面形成上述两个导电图形层。例如，可以通过电镀等工艺在介质基板110的表面设置金属薄层，之后通过蚀刻工艺去除介质基板110表面多余的金属以进行图形化，进而形成第一导电图形层120或者第二导电图形层130。
可选地，该金属薄层可以是铜箔、铝箔或者铍铜合金箔等。也就是说，此时第一导电图形层120和第二导电图形层130为金属层，第一信号线121、第二信号线131以及第二地线132等均为金属带状线。
如图13、图14中的(a)部分以及图15所示，第一导电图形层120还包括间隔设置于第一信号线121两侧的两个第一地线122，此时第一信号线121和两个第一地线122共同构成电路板100上的另一个平面波导传输线结构，也就是说，电路板100具有双层共面波导传输线结构。两个第二地线132各自通过金属化过孔140与对应一侧的第一地线122电连接。
如图13、图15所示，介质基板110上设置有多个金属化过孔140，金属化过孔140电气连接两侧的地线或者信号线。
具体地，第一信号线121与第二信号线131相对设置，二者在介质基板110上的投影至少部分重合，金属化过孔140垂直于介质基板110的表面，部分金属化过孔140位于该投影重合的区域内，进而能够电气连接两侧的第一信号线121与第二信号线131。
进一步地，由于第二信号线131包括相互分隔的多个传输线段131a，因此每个传输线段131a均通过至少一个金属化过孔140与第一信号线121电连接。
第一地线122与第二地线132相对设置，二者在介质基板110上的投影至少部分重合，部分金属化过孔140位于该投影重合的区域内，进而能够电气连接两侧的第一地线122与第二地线132，以保证第一地线122与第二地线132的电位相等。
各个金属化过孔140彼此之间的截面形状、大小可以相同，也可以不同，金属化过孔140的截面形状不限，例如可以为圆形、方形或者条形等。
可选地，在其他实施方式中，也可以通过其他方式来实现介质基板110两侧的地线或者信号线之间的电连接，本申请对此不做限定。例如，该其他方式可以是下文中介绍的金属化开槽结构。
如图13以及图14中的(b)部分所示，第二导电图形层130包括两个传输线段131a，上述两个传输线段131a通过断口133相互分隔，断口133内设置有连接桥134，连接桥134电气连接第二信号线131两侧的两个第二地线132。
可选地，第二地线132的宽度可以大于第二信号线131的宽度，例如第二地线132可以延伸至介质基板110两侧的边缘位置，通过以上设置能够尽可能的提高接地面的面积，以提高屏蔽效果。
图16是本申请实施例提供的电路板100的另一例的结构示意图。图17是图16所示的电路板的爆炸图。图18是图16所示的电路板100的俯视图和仰视图。其中，图18中的(a)部分是电路板100的俯视图，图18中的(b)部分是电路板100的仰视图。
如图16-图18所示，当信号传输的距离较长时，第二信号线131也可以被分割成更多个传输线段131a，此时具有更多个断口133，进而能够设置更多个连接桥134。
具体地，连接桥134与断口133可以均设置多个，每个连接桥134均位于断口133内。通过以上设置，能够在信号传输距离较长的情况下，因地制宜的设置更多个连接桥134，确保传输线段131a不会太长，即确保传输线段131a与第二地线132之间的开槽长度不会过大，由此保证了地平面的完整性和封闭性，即确保了地平面能够具有良好的屏蔽性能。此外，开槽长度过大不利于生产加工(铣刀切割路径太长容易出现误差)，本申请通过设置多个连接桥134来缩短开槽的长度，能够提高生产的效率，降低生产成本。
可选地，断口133的数量可以大于、等于或者小于连接桥134的数量。
可选地，不同断口133内设置的连接桥134的数量可以相同或者不同。
可选地，断口133内可以仅设置一个连接桥134，或者设置多个连接桥134，或者不设置连接桥134，本申请对此不做限定。
例如，断口133的数量大于连接桥134的数量，多个连接桥134一一对应的设置于多个断口133内，而由于断口133的数量更多，剩余的断口133内可以不设置连接桥134。
在本申请实施例中，如图17、图18所示，断口133的数量等于连接桥134的数量，多个连接桥134一一对应的设置于多个断口133内。通过以上设置，能够尽可能的增大导电图形在介质基板110上的覆盖面积，即增大地平面的面积，保证地平面的完整性和封闭性。此外还有利于简化加工程序，降低生产成本。
当信号传输的距离较长时，可以通过设置N个断口133将第二信号线131分隔成N+1个传输线段131a，在这里N为大于或者等于2的整数。例如，如图17、图18所示，可以通过3个断口133将第二信号线131分隔成4个传输线段131a，并且在这3个断口133种各设置一个连接桥134。
进一步地，在本申请实施例中，传输线段131a的长度小于第二信号线131所传输电磁波信号的0.5倍波长。通过以上设置，能够避免传输线段131a在其他电磁波信号的作用下发生谐振，进而能够确保第二信号线131传输的稳定性。此外，以上设置也可以作为一个将第二信号线131分割成多少个传输线段131a的参考依据。
图19是本申请实施例提供的电路板100的再一例的剖视图。图20是图19所示的电路板100的爆炸图。
前述连接桥134的相关设置不仅适用于图12-图18中的双面板，同样也适用于多层板。在本申请实施例中，如图19、图20所示，电路板100为多层板，具有多个板体，介质基板110为该多个板体中的任意一个。电路板100可以具有M个板体，并且具有M+1个导电图形层，相邻两个导电图形层之间通过一个板体分隔开，其中M为大于或者等于2的整数。在该M个板体完成金属图形化(即设置完成导电图形层)以后，通过相互堆叠压合以形成该电路板100。
可选地，第一导电图形层120可以为该M+1个导电图形层中的任意一个，例如可以是位于电路板100的顶面或者底面上的导电图形层，也可以是电路板100内部位于两个板体中间的一个导电图形层。
类似地，第二导电图形层130可以为该M+1个导电图形层中的任意一个，例如可以是位于电路板100的顶面或者底面上的导电图形层，也可以是电路板100内部位于两个板 体中间的一个导电图形层。
可选地，第一导电图形层120和第二导电图形层130之间可以仅具有一个板体，此时该一个板体即介质基板110。
可选地，第一导电图形层120和第二导电图形层130之间也可以具有多个板体，此时介质基板110为该多个板体中的一个。
如图19、图20所示，在本申请实施例中，电路板100具有三个板体和四个导电图形层，任意相邻的两个导电图形层之间均通过一个板体相互分隔。
具体地，电路板100由上至下依次包括第一导电图形层120、第三导电图形层160、第四导电图形层170以及第二导电图形层130，相邻两个导电图形层之间均通过一个板体相互分隔，相邻的导电图形层通过金属化过孔140电气连接。
在本申请实施例中，第一导电图形层120位于整个电路板100的顶面，第二导电图形层130位于整个电路板100的底面，此时介质基板110可以为三个板体中的任意一个，例如图中最下侧的一个板体。
可选地，第三导电图形层160可以包括共面波导传输线结构，该共面波导传输线结构可以和第一导电图形层120或者第二导电图形层130的传输线结构相同，本申请对此不做限定。
可选地，第四导电图形层170可以包括共面波导传输线结构，该共面波导传输线结构可以和第一导电图形层120或者第二导电图形层130的传输线结构相同，本申请对此不做限定。
综上所述，对于具有3层或者3层以上共面波导传输线结构的电路板100，可以在其中的一层或者多层共面波导传输线结构上进行上述连接桥134的相关设置，但需要保留至少一层波导传输线结构不设置连接桥134，使得该层中的信号线能够保持完整、前后接续，保证射频信号的正常传输。
如图19、图20所示，不同层之间的信号线、地线可以通过金属化过孔140电气连接。此时，由于第一导电图形层120和第二导电图形层130的相对位置不定，即介质基板110的位置也不定，由此使得至少需要贯穿介质基板110以连接第一导电图形层120和第二导电图形层130的金属化过孔140可以为通孔、盲孔或者埋孔。
在这里，通孔、盲孔或者埋孔是针对整个电路板100而言，通孔贯穿整个电路板100的底面和顶面。盲孔从电路板100的底面或者顶面穿入，而未贯穿整个电路板100。埋孔埋设于电路板100的内部，但未导通至外表面。
传统的共面波导虽然对降低传输线的介质损耗有一定作用，但是仍然有较大的电场分量集中在电路板的介质材料中。为了进一步降低传输线损耗，可以在共面波导的传输线两侧与地平面(地线)之间设置开槽，将部分介质去除，这样可以很大程度降低传输线的介质损耗。图21-图24示出了一种电路板100，通过设置开槽来降低传输线的介质损耗。
图21是本申请实施例提供的电路板100的再一例的结构示意图。图22是图21所示的电路板100的爆炸图。图23是图21所示的电路板100的俯视图和仰视图。图24是图21中BB视角的剖视图。其中，图23中的(a)部分是电路板100的俯视图，图23中的(b)部分是电路板100的仰视图。
如图21-图24所示，介质基板110上还设有介质开槽150，介质开槽150位于传输线 段131a与第二地线132之间。通过设置介质开槽150，能够将位于传输线段131a与第二地线132之间的部分介质挖除，由此使得传输线段131a产生的电场能够更多的分布于空气中，而减小电场在介质中的分布，进而能够进一步降低传输线的介质损耗，提高信号的传输质量。
如图22、图23中的(a)部分、图23中的(b)部分所示，介质开槽150需要以“分段开槽”的方式间隔设置多个，即在传输线段131a与第二地线132之间设置介质开槽150，而在需要设置连接桥134的地方保留介质，这样才能实现通过印制导体图形的方式将连接桥134设置于介质基板110上。
进一步地，介质开槽150为条形槽，并贯穿介质基板110的两侧，即此时介质开槽150为贯通介质基板110两侧的通槽，介质开槽150沿着传输线段131a的长度方向延伸设置。通过以上设置，能够挖除更多的介质，尽可能的减小电场在介质中的分布，进而能够进一步降低传输线的介质损耗，提高信号的传输质量。
可选地，在其他实施方式中，介质开槽150也可以为盲槽，此时介质开槽150并未贯穿介质基板110的两侧。
进一步地，介质开槽150的槽口边缘与第二导电图形层130的各部分金属图形的间距为0.05～0.3毫米。具体地，介质开槽150的槽口边缘与传输线段131a、第二地线132或者连接桥134之间的距离为0.05～0.3毫米。例如，可以为0.08毫米、0.1毫米、0.12毫米、0.15毫米或者0.2毫米等。
通过在槽口和金属图形之间设置一定的安全距离，能够在开槽制作的过程中，避免铣刀损伤金属图形(例如铜箔)边沿，形成金属毛刺和裸露铜箔，影响传输线抗腐蚀、抗氧化等方面的性能。
图25是本申请实施例提供的电路板100的再一例的结构示意图。图26是图25所示的电路板100的爆炸图。图27是图25所示的电路板100的俯视图和仰视图。图28是图25中CC视角的剖视图。其中，图27中的(a)部分是电路板100的俯视图，图27中的(b)部分是电路板100的仰视图。
如图25-图28所示，在本申请实施例中，介质开槽150邻近传输线段131a一侧的槽壁上设有第一导电侧壁151，传输线段131a通过第一导电侧壁151与第一信号线121电连接。介质开槽150邻近第二地线132一侧的槽壁上设有第二导电侧壁152，第二导电侧壁152与第一导电侧壁151电隔离，第二地线132通过第二导电侧壁152与第一地线122电连接。
通过以上设置，一方面，能够使得介质开槽150开设的尽量大，介质开槽150的槽口边缘可以靠近金属图形的边沿，使得第二信号线131与第二地线132之间的区域，除连接桥134覆盖的部分保留有少量介质外，其余部分的介质几乎全部被去除，电场主要分量分布在空气中，因此能够最大程度降低介质引起的传输线损耗。
另一方面，第一导电侧壁151与双层共面波导的信号线电连接，第二导电侧壁152双层共面波导的地线电连接，而第一导电侧壁151与第二导电侧壁152相互靠近且正对，由此能够增大信号线与地线的正对面积，线内的电流分布也更加均匀，由此减小了导体损耗，并降低了传输线的阻抗。
进一步地，如图26、图28所示，在本申请实施例中，由于第一导电侧壁151实现了 介质基板110两侧的信号线之间的电连接，第二导电侧壁152实现了介质基板110两侧的地线之间的电连接，由此使得前述实施例中的金属化过孔140可以省略。由此节约了生产工序和生产成本。第一导电侧壁151与第二导电侧壁152相互电隔离，使得一个介质开槽150同时实现了介质基板110两侧的信号线、地线的电连接。
在本申请实施例中，在介质开槽150内设置第一导电侧壁151与第二导电侧壁152的制作过程(即金属化侧壁)基本能够兼容现有双面板或多层板的制造工序，无需增加额外的制造工序，因此具备接近于零的实施成本。
图29是金属化侧壁制作过程的流程示意图。如图29中的(a)部分所示，首先提供已经在表面设置完整金属薄层(例如通过电镀形成的铜箔层)的基板，该基板可以是双面板(即仅包括一个介质基板)或者已经完成内层图形制作和压合的多层板(即包括多个介质基板)。如图29中的(b)部分所示，通过钻头在基板的预设位置进行金属化钻孔和金属化开槽。如图29中的(c)部分所示，在开设完成的孔和槽内进行电镀，使得金属薄层附着在孔壁和槽壁上，图中的虚线表示侧壁金属化。如图29中的(d)部分所示，进行非金属化钻孔，去除金属化槽壁两端的电镀孔壁，即形成前述两个相互电隔离的第一导电侧壁151与第二导电侧壁152。如图29中的(e)部分所示，最后通过蚀刻工艺去除基板表面多余的金属，以形成金属图形。
另一方面，本申请实施例还提供了一种天线结构。图30是本申请提供的天线结构的结构示意图。如图30所示，本申请实施例提供的天线结构包括天线单元200以及前述任一实施例所提供的电路板100，该天线结构为定向天线，天线单元200设于电路板100的一侧，电路板100构成天线单元200的反射板。
可选地，该天线结构可以是有源天线或者无源天线。
可选地，天线单元200可以为偶极子天线。
可选地，天线单元200可以包括多个，并且以阵列的形式排布于电路板100之上。
可选地，天线单元200与电路板100电气连接，例如电路板100上的传输线结构可以作为天线单元200的馈线。
由于前述实施例提供的电路板100保证了地平面的完整性和封闭性(或者说，没有破坏地平面的完整性)，能够降低电路板100对外部元器件产生的电磁辐射干扰，因此电路板100能够作为定向天线的反射板使用，而不会影响天线的方向图性能。下面以一个具体的仿真实例进行说明。
在本仿真实例中，天线单元200为偶极子天线，前述图25-图28所示的电路板100作为天线单元200的反射板，传输线的长度为150毫米，采用与前述图10相同的仿真场景，唯一的不同点是采用本申请实施例提供的具有连接桥134的双层共面波导传输线结构取代常规的双层共面波导传输线结构。
图31是本申请实施例提供的天线结构的辐射方向图。对比图21和前述的图6可以看出，天线方向图没有出现明显恶化，这是因为由于连接桥134的设置避免了在地平面上出现长度很大的开槽，保证了地平面的封闭性和完整性。
由于天线结构采用了上述实施例提供的电路板100，因此使得天线结构也具有与电路板100相应的技术效果，在此不再赘述。
再一方面，本申请实施例还提供了一种电子设备，该电子设备包括壳体以及前述任一 实施例所提供的电路板100，电路板100位于壳体内。
可选地，该电子设备可以是手持设备、车载设备、可穿戴设备、计算设备或连接到无线调制解调器的其它处理设备。
例如，该电子设备可以是手机、平板电脑、笔记本电脑、智能手表、智能手环、智能眼镜或者智能电视(智慧屏)等。
可选地，该电子设备可以是通信设备，例如可以是基站或者雷达。
此时，电子设备还包括前述的天线单元200，该天线单元200设于电路板100的一侧，电路板100构成天线单元200的反射板。也就是说，该电子设备还可以包括前述实施例提供的天线结构，该天线结构设于壳体内。
由于电子设备采用了上述实施例提供的电路板100，因此使得电子设备也具有与电路板100相应的技术效果，在此不再赘述。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (18)

  1. 一种电路板，其特征在于，包括：
    介质基板(110)，由绝缘材料构成；
    第一导电图形层(120)，设于所述介质基板(110)的一侧，所述第一导电图形层(120)包括第一信号线(121)；
    第二导电图形层(130)，设于所述介质基板(110)的另一侧，所述第二导电图形层(130)包括第二信号线(131)以及间隔设置于所述第二信号线(131)两侧的两个第二地线(132)；
    所述第二信号线(131)包括排成一列的多个传输线段(131a)，相邻两个所述传输线段(131a)之间具有断口(133)，所述第二导电图形层(130)还包括与所述第二信号线(131)电隔离的连接桥(134)，所述连接桥(134)位于所述断口(133)内并且电气连接两个所述第二地线(132)，每个所述传输线段(131a)与所述第一信号线(121)电连接。
  2. 根据权利要求1所述的电路板，其特征在于，所述连接桥(134)与所述断口(133)均为多个，每个所述连接桥(134)均位于所述断口(133)内。
  3. 根据权利要求2所述的电路板，其特征在于，所述连接桥(134)与所述断口(133)的数量相等，多个所述连接桥(134)与多个所述断口(133)一一对应。
  4. 根据权利要求1-3中任一项所述的电路板，其特征在于，所述传输线段(131a)的长度小于所述第二信号线(131)所传输电磁波信号的0.5倍波长。
  5. 根据权利要求1-4中任一项所述的电路板，其特征在于，每个所述传输线段(131a)通过金属化过孔(140)与所述第一信号线(121)电连接。
  6. 根据权利要求1-4中任一项所述的电路板，其特征在于，所述第一导电图形层(120)还包括间隔设置于所述第一信号线(121)两侧的两个第一地线(122)，所述第二地线(132)与所述第一地线(122)电连接。
  7. 根据权利要求6所述的电路板，其特征在于，所述介质基板(110)上还设有介质开槽(150)，所述介质开槽(150)位于所述传输线段(131a)与所述第二地线(132)之间。
  8. 根据权利要求7所述的电路板，其特征在于，所述介质开槽(150)为条形槽，并贯穿所述介质基板(110)的两侧，所述介质开槽(150)沿着所述传输线段(131a)的长度方向延伸设置。
  9. 根据权利要求8所述的电路板，其特征在于，所述介质开槽(150)邻近所述传输线段(131a)一侧的槽壁上设有第一导电侧壁(151)，所述传输线段(131a)通过所述第一导电侧壁(151)与所述第一信号线(121)电连接；
    所述介质开槽(150)邻近所述第二地线(132)一侧的槽壁上设有第二导电侧壁(152)，所述第二导电侧壁(152)与所述第一导电侧壁(151)电隔离，所述第二地线(132)通过所述第二导电侧壁(152)与所述第一地线(122)电连接。
  10. 根据权利要求6所述的电路板，其特征在于，所述第二地线(132)通过金属化过孔(140)与所述第一地线(122)电连接。
  11. 根据权利要求7-9中任一项所述的电路板，其特征在于，所述介质开槽(150)的槽口边缘与所述传输线段(131a)、所述第二地线(132)或者所述连接桥(134)之间的距离为0.05～0.3毫米。
  12. 根据权利要求5所述的电路板，其特征在于，所述金属化过孔(140)为通孔、盲孔或者埋孔。
  13. 根据权利要求1-12中任一项所述的电路板，其特征在于，所述电路板为双面板。
  14. 根据权利要求1-12中任一项所述的电路板，其特征在于，所述电路板为具有多个板体的多层板，所述介质基板(110)为所述多个板体中的任意一个。
  15. 根据权利要求1-14中任一项所述的电路板，其特征在于，所述第二导电图形层(130)为由蚀刻工艺制成的金属层。
  16. 一种天线结构，其特征在于，包括天线单元(200)和如权利要求1-15中任一项所述的电路板，所述天线单元(200)设于所述电路板的一侧，所述电路板构成所述天线单元(200)的反射板。
  17. 一种电子设备，其特征在于，包括壳体和如权利要求1-15中任一项所述的电路板，所述电路板位于所述壳体内。
  18. 根据权利要求17所述的电子设备，其特征在于，所述电子设备还包括位于所述壳体内的天线单元(200)，所述天线单元(200)设于所述电路板的一侧，所述电路板构成所述天线单元(200)的反射板。
PCT/CN2022/093556 2021-08-13 2022-05-18 电路板、天线结构及电子设备 WO2023016024A1 (zh)

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JP2003318610A (ja) * 2002-04-26 2003-11-07 Asahi Glass Co Ltd 高周波平面回路
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