A high speed signal transmission circuit board assembly

Abstract

The application relates to a high-speed signal transmission circuit board assembly, belonging to the field of high-speed interconnection and printed circuit boards, which comprises two circuit board layers arranged oppositely and an intermediate support located between the two circuit board layers, each circuit board layer is provided with a signal interface area and a grounding layer, a first hollowing-out area corresponding to each signal interface area is formed on the intermediate support, so that an air medium cavity is formed between the signal interface area and the intermediate support after assembly, the air medium has a relatively low dielectric constant compared with other materials, thereby improving the characteristic impedance of the signal interface layer, the hollowing-out structure is arranged on the intermediate support, the hollowing-out area of the grounding area can be reduced, and the problem that electromagnetic shielding is lost between adjacent signal interfaces due to the large-area hollowing-out of the grounding area is reduced, the air medium cavity bears the function of improving the impedance, the internal grounding layer of the circuit board layer retains the function of electromagnetic shielding, and the technical effects of impedance matching and signal crosstalk suppression are considered.

Description

Technical Field

[0001] This application relates to the field of high-speed interconnects and printed circuit boards, and in particular to a high-speed signal transmission circuit board assembly. Background Technology

[0002] High-speed transmission PCBs (Printed Circuit Boards) are carriers for realizing high-speed digital signal transmission. They are widely used in the internal and inter-device high-speed interconnection of equipment in fields such as servers, data centers, communication base stations, and high-performance computing. With the continuous improvement of data transmission rate, the signal rate of the current mainstream high-speed serial interface has generally reached 10Gbps or more, and is even evolving towards 56Gbps and 112Gbps. This has put forward stringent requirements for the signal integrity design of PCBs.

[0003] In the design of high-speed transmission PCBs, characteristic impedance control and signal crosstalk suppression are two core technical indicators. The continuity of characteristic impedance directly affects signal reflection and loss, while signal crosstalk directly affects the bit error rate and system reliability of signal transmission.

[0004] In related technologies, high-speed transmission PCBs typically employ multi-layer board structures, such as four-layer or six-layer boards. Taking a common four-layer board as an example, the outer two layers are signal trace layers, and the middle two layers are complete ground layers (GND layers). Signal interface areas are located at both ends of the signal trace layers. These signal interface areas typically include gold fingers, pads, connector pins, BGA pads, etc., serving as the physical interface for high-speed signal input and output. The middle GND layer mainly performs two functions: first, it serves as the characteristic impedance reference ground for the signal trace transmission lines; second, it serves as the crosstalk shielding ground between adjacent signal lines. The physical size of the signal interface area is usually much larger than the width of conventional signal traces. This leads to a decrease in the local characteristic impedance of this area, causing a mismatch with the characteristic impedance of the signal traces, which in turn causes problems such as signal reflection and increased insertion loss.

[0005] To address the impedance mismatch issue in the signal interface area, the common approach in existing technologies is to perform a large-area hollowing-out process on the GND layer directly below the signal interface area. This involves removing the metal from the GND layer at that location to form a rectangular or other shaped hollowed-out area. By increasing the distance between the signal interface area and the reference ground plane, the local characteristic impedance of this area is improved, making it as close as possible to the characteristic impedance of the signal trace.

[0006] However, because the GND layer is largely hollowed out directly below the signal interface area, the electromagnetic shielding effect of the GND layer is completely lost between adjacent signal interfaces in this area. The electric and magnetic fields between adjacent signal interfaces (such as adjacent gold fingers and adjacent pads) cannot be effectively isolated, resulting in a significant increase in signal crosstalk. In high-speed transmission scenarios above 10Gbps, this crosstalk can lead to an increase in the bit error rate. It is evident that while existing technologies hollow out the GND layer to increase impedance, they also damage the integrity of the grounding layer, causing a serious decrease in the crosstalk suppression capability of the signal interface area. This presents a technical defect where impedance matching and signal crosstalk suppression are difficult to achieve simultaneously. Summary of the Invention

[0007] To address the aforementioned problems, this application provides a high-speed signal transmission circuit board assembly.

[0008] This application provides a high-speed signal transmission circuit board assembly with the following technical solution: it includes two circuit board layers arranged opposite each other and an intermediate support located between the two circuit board layers. The stacked structure of the two circuit board layers is symmetrically arranged with respect to the intermediate support. Each circuit board layer is provided with a signal interface area and a ground area. The intermediate support has a first hollow area that penetrates its own thickness. The position of the first hollow area is aligned vertically with the signal interface areas of the two circuit board layers, so that after assembly, the first hollow area is closed by the circuit board layers on both sides, thereby forming an air medium cavity between the signal interface areas of the two circuit board layers.

[0009] By adopting the above technical solution, a first hollowed-out area penetrating the thickness of the intermediate support is opened, and after assembly, it is sealed by the circuit board layers on both sides, thereby forming an air dielectric cavity between the signal interface areas of the two circuit board layers. Utilizing the characteristic that the dielectric constant of air is about 1.0, which is much lower than that of conventional solid materials, the equivalent dielectric constant around the signal interface area is significantly reduced, thereby increasing the characteristic impedance of the signal interface area and helping to achieve matching with the characteristic impedance of the signal traces. This solution transfers the hollowed-out area from the GND layer inside the circuit board layer to the intermediate support between the two circuit board layers, which can reduce the hollowed-out area of ​​the grounding area and reduce the problem of loss of electromagnetic shielding between adjacent signal interfaces due to the large-area hollowing out of the grounding area. Thus, by spatially separating the impedance enhancement function and the electromagnetic shielding function, the air dielectric cavity undertakes the function of enhancing impedance, while the grounding layer inside the circuit board layer retains the function of electromagnetic shielding, thus taking into account the technical effects of impedance matching and signal crosstalk suppression.

[0010] Preferably, the signal interface area includes a plurality of gold fingers and a plurality of solder pads, and the first hollow area is correspondingly divided into a first hollow structure corresponding to the plurality of gold fingers and a second hollow structure corresponding to the plurality of solder pads.

[0011] By adopting the above technical solution, the first hollow area on the intermediate support is correspondingly divided into a first hollow structure corresponding to the gold finger and a second hollow structure corresponding to the pad, so that air dielectric cavities are independently formed under the gold finger and under the pad. The air dielectric cavities reduce the equivalent dielectric constant between the corresponding gold finger and the corresponding pad on the two circuit board layers, thereby improving the characteristic impedance of the gold finger and the pad respectively, which helps to match the characteristic impedance of the gold finger and the pad with the characteristic impedance of the signal trace.

[0012] Preferably, each circuit board layer includes a PCB board, a hollowed-out circuit board, and a signal circuit board stacked sequentially. The grounding area is disposed on the hollowed-out circuit board, the signal interface area is disposed on the signal circuit board, and the signal circuit board and the hollowed-out circuit board are disposed on both sides of the PCB board. The hollowed-out circuit board is located on the side of the PCB board closer to the intermediate support, and the signal circuit board is located on the side of the PCB board away from the intermediate support.

[0013] By adopting the above technical solution, the signal circuit board is directly placed on the side of the PCB board away from the intermediate support, and the hollowed-out circuit board is placed on the side of the PCB board closer to the intermediate support as a grounding area. The thickness of the PCB board precisely defines the dielectric spacing between the signal interface area and the ground reference layer, thus providing a stable and easily adjustable physical basis for impedance control. At the same time, the hollowed-out circuit board is adjacent to the first hollowed-out area of ​​the intermediate support, so that the dielectric environment under the signal circuit board is jointly formed by the PCB board and the air dielectric cavity. With the help of the low dielectric constant and stable electrical characteristics of air, the equivalent dielectric constant of the signal interface area is effectively reduced, reducing dielectric loss and impedance fluctuation. The hollowed-out circuit board can provide a continuous low-impedance return path and good electromagnetic shielding, suppressing signal crosstalk and external interference, thereby achieving more accurate and stable impedance matching in the signal interface area and ensuring the integrity and transmission quality of high-frequency signals.

[0014] Preferably, each of the hollowed-out circuit boards is provided with a second hollowed-out area, the second hollowed-out area including a third hollowed-out structure corresponding to the gold finger and a fourth hollowed-out structure corresponding to the solder pad.

[0015] By adopting the above technical solution, the circuit board is hollowed out to form a grounding area. By selectively removing the grounding layer metal directly below the gold fingers and pads, the air dielectric volume between the signal interface area and the ground reference plane is further increased, reducing the parasitic capacitance and equivalent dielectric constant at the gold fingers and pads, making the impedance closer to the target value. At the same time, a third and fourth hollowing structure are set up to address the structural differences between the gold fingers and pads, which can independently optimize the impedance characteristics of the gold fingers and pads. This allows for more accurate and consistent impedance matching at the gold fingers and pads, effectively reducing signal reflection and insertion loss caused by impedance discontinuity, and ensuring the integrity and stability of high-frequency signals transmitted through the gold fingers and pads.

[0016] Preferably, the second hollowed-out area is through-hole along the thickness direction of the hollowed-out circuit board.

[0017] By adopting the above technical solution, the second hollowed-out area is set through the thickness direction of the hollowed-out circuit board, forming a continuous air dielectric cavity with the first hollowed-out area that penetrates its own thickness on the intermediate support in the vertical direction. This makes the dielectric environment below the signal interface area composed of a larger volume and purer air dielectric, further reducing the equivalent dielectric constant at the gold finger and pad, thereby significantly improving the characteristic impedance. At the same time, the through connection between the first and second hollowed-out areas makes the spatial relationship between the ground reference surface of the hollowed-out circuit boards on both sides and the intermediate support clearer and more consistent, reducing impedance fluctuations and mode conversions caused by local dielectric inhomogeneity.

[0018] Preferably, the third hollowed-out structure is provided with a shielding part.

[0019] By adopting the above technical solution, a shielding part is set in the third hollow structure. The shielding part introduces a local grounding reference structure in the gold finger. It can compensate for the impedance value while maintaining the low dielectric constant of the air medium to improve the characteristic impedance. At the same time, the shielding part, as a grounded electromagnetic isolation barrier, can effectively absorb and suppress electromagnetic crosstalk of the gold finger. Thus, while ensuring accurate impedance matching, it improves the signal integrity and anti-interference ability of the gold finger.

[0020] Preferably, each PCB board has a first connection area corresponding to the position of the solder pad, and each PCB board has a second connection area corresponding to the position of the gold finger.

[0021] By adopting the above technical solution, each PCB board has a first connection area corresponding to the pad position and a second connection area corresponding to the gold finger position. The first and second connection areas provide independent interlayer electrical interconnection channels for the pad and gold finger, respectively, enabling the pad and gold finger to establish electrical connection with the hollowed-out circuit board below through the PCB board. The separate setting of the first and second connection areas can be differentiated according to the working characteristics of the pad and gold finger, reducing signal interference caused by shared connection paths. At the same time, the first and second connection areas form corresponding grounding points on the PCB board, providing short and direct return paths for the pad and gold finger, reducing parasitic inductance and grounding impedance, enhancing the consistency of signal loops, and thus synergistically improving the overall impedance matching accuracy and high-frequency signal transmission stability of the signal interface area.

[0022] Preferably, the intermediate support has at least one column on each of the circuit board layers on both sides, and the column passes through two hollowed-out circuit boards, the PCB board and the signal circuit board in sequence.

[0023] By adopting the above technical solution, at least one column is provided on the circuit board layers on both sides of the intermediate support. The column passes through two hollowed-out circuit boards, a PCB board and a signal circuit board in sequence. The column provides mechanical positioning and interlayer fixation for the intermediate support and the circuit board layers on both sides, ensuring the vertical alignment of the first hollowed-out area and the second hollowed-out area, thereby ensuring the structural integrity and consistency of the air dielectric cavity. At the same time, the column passes through the signal interface area and connects to the hollowed-out circuit boards on both sides as grounding layers, constructing a low-impedance vertical grounding path that runs through the hollowed-out circuit boards on both sides as grounding layers, effectively balancing the grounding potential, reducing the inductance of the grounding loop, and enhancing the electromagnetic shielding continuity of the overall structure.

[0024] Preferably, each column has a block at one end near the signal interface area, each PCB board has a third connection area corresponding to the position of the block, and each signal circuit board is disposed between the corresponding third connection area and the corresponding block.

[0025] By adopting the above technical solution, a third connection area is set at the position of each block on each PCB board. Each signal circuit area is set between the corresponding third connection area and the corresponding block. The block extends the grounding path of the column to the vicinity of the signal circuit board through the third connection area, minimizing the electrical distance between the signal circuit board and the grounding structure. This creates a local grounding reference plane that is close to the signal within the signal circuit board, effectively reducing the parasitic inductance of the signal return path and enhancing the local electromagnetic shielding effectiveness. At the same time, the block and the third connection area form a clamping connection structure in the vertical direction, which enhances the mechanical fixing strength between the signal circuit area and the PCB board and the column, reduces interlayer micro-movements caused by vibration or thermal expansion and contraction, and ensures the electrical connection stability and structural reliability of the signal circuit area during long-term operation.

[0026] Preferably, it also includes a connecting plate and a plurality of wires, the intermediate bracket being embedded in the connecting plate, and each of the wires passing through the connecting plate and being soldered to the corresponding pad.

[0027] By adopting the above technical solution, the connecting plate provides an integrated load-bearing foundation for the intermediate support and the wires. The intermediate support is embedded in the connecting plate. Each wire passes through the connecting plate and is welded to the corresponding pad. The connecting plate provides a stable mechanical support and precise spatial positioning between the intermediate support and the pad, so that the wires maintain a certain direction and spacing on the path of passing through, reducing the stress concentration of the solder joint caused by the displacement of the wires due to vibration or external force, and ensuring the long-term reliability of the solder joint. At the same time, the wires pass through the connecting plate and are directly welded to the pad. The wires are separated by the solidity of the connecting plate, which effectively suppresses crosstalk between adjacent channels.

[0028] In summary, this application includes at least one of the following beneficial technical effects: 1. A first hollow area penetrating the thickness of the intermediate support is opened, and after assembly, it is sealed by the circuit board layers on both sides, thereby forming an air dielectric cavity between the signal interface areas of the two circuit board layers. Taking advantage of the characteristic that the dielectric constant of air is about 1.0, which is much lower than that of conventional solid materials, the equivalent dielectric constant around the signal interface area is significantly reduced, which improves the characteristic impedance of the signal interface area and helps to achieve matching with the characteristic impedance of the signal trace. 2. By moving the hollowed-out area from the GND layer inside the circuit board layer to the intermediate support between the two circuit board layers, the hollowed-out area of ​​the grounding region can be reduced. This reduces the problem of loss of electromagnetic shielding between adjacent signal interfaces due to a large area of ​​the grounding region being hollowed out. Thus, the impedance boosting function and the electromagnetic shielding function are spatially separated. The air dielectric cavity undertakes the function of boosting impedance, while the grounding layer inside the circuit board layer retains the function of electromagnetic shielding, thus achieving both impedance matching and signal crosstalk suppression technical effects. 3. A shielding part is set in the third hollow structure. The shielding part introduces a local grounding reference structure in the gold finger. It can compensate for the impedance value while maintaining the low dielectric constant of the air medium to improve the characteristic impedance. At the same time, the shielding part, as a grounded electromagnetic isolation barrier, can effectively absorb and suppress electromagnetic crosstalk of the gold finger. Thus, while ensuring accurate impedance matching, it improves the signal integrity and anti-interference ability of the gold finger. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the circuit board layer and intermediate support structure in an embodiment of this application.

[0030] Figure 2 This is a schematic diagram of the separate structure of the circuit board layer and the intermediate support in an embodiment of this application.

[0031] Figure 3 This is a schematic diagram of the separate structure of the circuit board layer and the intermediate support in an embodiment of this application.

[0032] Figure 4 This is a schematic diagram of the signal circuit board in an embodiment of this application.

[0033] Figure 5 This is a schematic diagram of the separate structure of the circuit board layers in an embodiment of this application.

[0034] Figure 6 This is a schematic diagram of the hollowed-out circuit board in an embodiment of this application.

[0035] Figure 7 This is a schematic diagram of the hollowed-out circuit board and signal circuit board in the embodiments of this application.

[0036] Figure 8 This is a schematic diagram of the hollowed-out circuit board and intermediate support in the embodiments of this application.

[0037] Figure 9 This is a schematic diagram of the structure of the intermediate support in the embodiments of this application.

[0038] Figure 10 This is a schematic diagram of the PCB board structure in an embodiment of this application.

[0039] Figure 11 This is a structural schematic diagram of an embodiment of this application.

[0040] Figure 12 This is a structural schematic diagram of an embodiment of this application.

[0041] Explanation of reference numerals in the attached drawings: 1. Circuit board layer; 11. Signal circuit board; 111. Gold finger; 112. Solder pad; 12. PCB board; 121. First connection area; 122. Second connection area; 123. Third connection area; 13. Hollowed-out circuit board; 131. Second hollowed-out area; 1311. Third hollowed-out structure; 1312. Fourth hollowed-out structure; 2. Intermediate support; 21. First hollowed-out area; 211. First hollowed-out structure; 212. Second hollowed-out structure; 22. Column; 221. Block; 3. Connecting plate; 4. Wire. Detailed Implementation

[0042] The following is in conjunction with the appendix Figure 1-12 This application will be described in further detail.

[0043] This application discloses a high-speed signal transmission circuit board assembly, referring to... Figure 1 , Figure 2 as well as Figure 3 It includes two circuit board layers 1 arranged opposite each other and an intermediate support 2 located between the two circuit board layers 1. The stacked structure of the two circuit board layers 1 is symmetrically arranged with respect to the intermediate support 2. Each circuit board layer 1 is provided with a signal interface area and a ground area. The signal interface area is used to realize the input and output of high-speed signals, and the ground area is used to provide signal return path and electromagnetic shielding. The signal interface area includes several gold fingers 111 and several pads 112.

[0044] Correspondingly, the material of the intermediate support 2 can be either plastic or metal, depending on the application requirements. The intermediate support 2 has a first hollowed-out area 21 that penetrates its own thickness. The first hollowed-out area 21 penetrates the first hollowed-out groove. The position of the first hollowed-out area 21 is aligned vertically with the signal interface areas of the two circuit board layers 1, as shown in the reference. Figure 4 The first hollowed-out area 21 is correspondingly divided into a first hollowed-out structure 211 corresponding to a plurality of gold fingers 111 and a second hollowed-out structure 212 corresponding to a plurality of pads 112. In this embodiment, there are 24 gold fingers 111 and 24 pads 112, and 12 first hollowed-out structures 211, that is, one first hollowed-out structure 211 for every two gold fingers 111. There are also 12 second hollowed-out structures 212, that is, one second hollowed-out structure 212 for every two pads 112.

[0045] Furthermore, after assembly, the first hollowed-out area 21 is sealed by the two circuit board layers 1, thereby forming an air dielectric cavity between the signal interface areas of the two circuit board layers 1. The dielectric constant of the air in the air dielectric cavity is close to 1.0, which is much lower than the dielectric constant of conventional printed circuit board dielectric materials such as FR-4. By utilizing the low dielectric constant and stable electrical characteristics of the air dielectric, the equivalent dielectric constant around the signal interface area is significantly reduced, which fundamentally improves the characteristic impedance of the signal interface area and helps to achieve matching with the characteristic impedance of the signal traces. More importantly, this scheme transfers the hollowed-out area from the ground layer inside the circuit board layer 1 to the intermediate support 2 between the two circuit board layers 1. This can reduce the hollowed-out area of ​​the ground area and reduce the problem of loss of electromagnetic shielding between adjacent signal interfaces due to the large-area hollowing out of the ground area. Thus, the electromagnetic shielding function of the ground area between adjacent signal interfaces is completely preserved in the structure, effectively suppressing signal crosstalk between adjacent gold fingers 111 and between adjacent pads 112. It achieves the separation of impedance enhancement function and electromagnetic shielding function in space, taking into account the technical effects of impedance matching and signal crosstalk suppression.

[0046] Reference Figure 5 Correspondingly, each circuit board layer 1 includes a PCB board 12, a hollowed-out circuit board 13, and a signal circuit board 11 stacked sequentially. The grounding area is located on the hollowed-out circuit board 13, and the signal interface area is located on the signal circuit board 11. The signal circuit board 11 and the hollowed-out circuit board 13 are located on opposite sides of the PCB board 12. The hollowed-out circuit board 13 is located on the side of the PCB board 12 closer to the intermediate support 2, and the signal circuit board 11 is located on the side of the PCB board 12 away from the intermediate support 2. Thus, the thickness of the PCB board 12 precisely defines the dielectric spacing between the signal interface area and the ground reference layer, preventing interference. The anti-control provides a stable and easily adjustable physical basis. The hollowed-out circuit board 13 is adjacent to the first hollowed-out area 21 of the intermediate support 2, so that the dielectric environment under the signal circuit board 11 is jointly formed by the PCB board 12 and the air dielectric cavity. With the help of the low dielectric constant and stable electrical characteristics of air, the equivalent dielectric constant of the signal interface area is effectively reduced, and dielectric loss and impedance fluctuation are reduced. The hollowed-out circuit board 13, as a continuous low impedance return path and electromagnetic shielding surface, can suppress signal crosstalk and external interference, and achieve more accurate and stable impedance matching in the signal interface area, ensuring the integrity and transmission quality of high frequency signals.

[0047] Reference Figure 6 and Figure 7Furthermore, each hollowed-out circuit board 13 is provided with a second hollowed-out area 131. The second hollowed-out area 131 is provided through the thickness direction of the hollowed-out circuit board 13. The second hollowed-out area 131 includes a third hollowed-out structure 1311 corresponding to the gold fingers 111 and a fourth hollowed-out structure 1312 corresponding to the pads 112. There are twelve third hollowed-out structures 1311, with one third hollowed-out structure 1311 corresponding to every two gold fingers 111. There are also twelve fourth hollowed-out structures 1312, with one fourth hollowed-out structure 1312 corresponding to every two pads 112.

[0048] Specifically, the third hollow structure 1311 is a through third hollow groove with a rectangular opening. The third hollow structure 1311 is provided with a shielding part, which is a cross-shaped hollow structure, so that a cross-shaped hollow pattern is formed on each hollow circuit board 13 corresponding to the gold finger 111. The cross-shaped hollow structure includes a first rod and a second rod, which are arranged to cross each other. The two ends of the first rod and the second rod are fixedly connected to the groove wall of the third hollow groove. The fourth hollow structure 1312 is a through fourth hollow groove. The fourth hollow structure 1312 is provided with a third rod along the width direction parallel to the hollow circuit board 13, and the third rod divides the fourth hollow structure 1312 into two parts.

[0049] This demonstrates that by selectively removing the ground layer metal directly beneath the gold finger 111 and pad 112, the air volume between the signal interface area and the ground reference plane is further increased, significantly reducing the parasitic capacitance and equivalent dielectric constant at the gold finger 111 and pad 112, making the impedance closer to the target value. By setting a third hollow structure 1311 and a fourth hollow structure 1312 to address the structural differences between the gold finger 111 and pad 112, the impedance characteristics of the gold finger 111 and pad 112 can be independently optimized. This allows for more precise and consistent impedance matching at both the gold finger 111 and pad 112, effectively reducing signal reflection and insertion loss caused by impedance discontinuities, and ensuring the integrity and stability of high-frequency signals transmitted through the gold finger 111 and pad 112.

[0050] Meanwhile, a shielding part is provided in the third hollowing structure 1311. The shielding part introduces a local grounding reference structure in the gold finger 111. It can finely compensate the impedance value while maintaining the low dielectric constant of the air medium to improve the characteristic impedance, and reduce the impedance deviation caused by excessive hollowing. At the same time, the shielding part, as a grounded electromagnetic isolation barrier, can effectively absorb and suppress the electromagnetic crosstalk of the gold finger 111. While ensuring accurate impedance matching, it improves the signal integrity and anti-interference ability of the gold finger 111.

[0051] Furthermore, the second hollowed-out region 131 is disposed through the thickness direction of the hollowed-out circuit board 13, forming a continuous air dielectric cavity with the first hollowed-out region 21 that penetrates its own thickness on the intermediate support 2 in the vertical direction. This reduces the dielectric interface and solid material residue between the hollowed-out circuit board 13 and the intermediate support 2, making the dielectric environment below the signal interface area composed of a larger volume and purer air dielectric, further reducing the equivalent dielectric constant at the gold finger 111 and the pad 112, thereby improving the characteristic impedance.

[0052] Reference Figure 8 and Figure 9 Meanwhile, the through connection between the first hollowed-out area 21 and the second hollowed-out area 131 makes the spatial relationship between the ground reference surface of the hollowed-out circuit boards 13 on both sides and the middle support 2 clearer and more consistent, reducing impedance fluctuations and mode conversions caused by local dielectric inhomogeneity, and synergistically enhancing the impedance control accuracy of the signal interface area and the stability of high-frequency signal transmission in the overall structure.

[0053] Reference Figure 10 Furthermore, each PCB board 12 has a first connection area 121 corresponding to the position of the pad 112, and a second connection area 122 corresponding to the position of the gold finger 111. The first connection area 121 and the second connection area 122 provide independent interlayer electrical interconnection channels for the pad 112 and the gold finger 111, respectively, so that the pad 112 and the gold finger 111 can establish an electrical connection with the hollow circuit board 13 below through the PCB board 12. The independent connection structure of the first connection area 121 and the second connection area 122 can be arranged differently according to the working characteristics of the pad 112 and the gold finger 111, reducing signal interference caused by the shared connection path.

[0054] Meanwhile, the first connection area 121 and the second connection area 122 form corresponding grounding points on the PCB board 12, providing a short and direct return path for the pad 112 and the gold finger 111, reducing parasitic inductance and grounding impedance, enhancing the consistency of the signal loop, and synergistically improving the overall impedance matching accuracy and high-frequency signal transmission stability of the signal interface area.

[0055] Reference Figure 4 and Figure 5Furthermore, the intermediate support 2 has at least one pillar 22 on each side of the circuit board layer 1. In this embodiment, the intermediate support 2 has three pillars 22 on each side of the circuit board layer 1. The three pillars 22 are arranged parallel to each other along the length of the intermediate support 2. The pillars 22 pass through two hollowed-out circuit boards 13, PCB board 12 and signal circuit board 11 in sequence. The pillars 22 provide mechanical positioning and interlayer fixation for the intermediate support 2 and the circuit board layers 1 on both sides, ensuring the vertical alignment of the first hollowed-out area 21 and the second hollowed-out area 131, thereby ensuring the structural integrity and consistency of the air dielectric cavity. At the same time, the pillars 22 penetrate the signal interface area and connect to the hollowed-out circuit boards 13 on both sides as grounding layers, constructing a low-impedance vertical grounding path that penetrates the grounding layers on both sides, effectively balancing the grounding potential, reducing the inductance of the grounding loop, and enhancing the electromagnetic shielding continuity of the overall structure. The pillars 22 form a grounding isolation barrier in the signal interface area, which can suppress signal crosstalk between the gold finger 111 and the pad 112, further improving the integrity and anti-interference capability of high-frequency signal transmission.

[0056] In addition, each column 22 has a block 221 near the signal interface area. The block 221 is hemispherical. Each PCB board 12 has a third connection area 123 corresponding to the position of the block 221. Each signal circuit board 11 is located between the corresponding third connection area 123 and the corresponding block 221. The planar area of ​​the block 221 is in contact with the signal circuit board 11. The block 221 extends the grounding path of the column 22 to the vicinity of the signal circuit board 11 through the third connection area 123, minimizing the electrical distance between the signal circuit board 11 and the grounding structure. This creates a local grounding reference surface adjacent to the signal within the signal circuit board 11, effectively reducing the parasitic inductance of the signal return path and enhancing the local electromagnetic shielding effectiveness. At the same time, the block 221 and the third connection area 123 form a clamping connection structure in the vertical direction, enhancing the mechanical fixing strength between the signal circuit board 11, the PCB board 12, and the column 22, reducing interlayer micro-movements caused by vibration or thermal expansion and contraction, and ensuring the electrical connection stability and structural reliability of the signal circuit board 11 during long-term operation.

[0057] Reference Figure 11 and 12Furthermore, the high-speed signal transmission circuit board assembly also includes a connecting plate 3 and several wires 4. The intermediate support 2 is embedded in the connecting plate 3, and each wire 4 passes through the connecting plate 3 and is soldered to the corresponding pad 112. The connecting plate 3 provides an integrated load-bearing foundation for the intermediate support 2 and the wires 4, providing stable mechanical support and precise spatial positioning between the intermediate support 2 and the pad 112. This ensures that the wires 4 maintain a definite direction and spacing on the path of insertion, reducing stress concentration at the solder joints caused by displacement of the wires 4 due to vibration or external forces, and ensuring the long-term reliability of the solder joints. The wires 4 pass through the connecting plate 3 and are directly soldered to the pad 112. The wires 4 are physically separated by the connecting plate 3, effectively suppressing crosstalk between adjacent channels and ensuring the high-frequency transmission quality of the signal led out from the pad 112 and the stability of the overall electrical connection.

[0058] Furthermore, the high-speed signal transmission circuit board assembly provided in this application can be widely used in various high-speed serial interface products. For example, the arrangement, spacing, and shape of the gold fingers 111 on the signal circuit board 11 can be adapted to the MiniSAS interface standard, MiniSAS HD interface standard, SlimSAS interface standard, LP SlimSAS interface standard, MCIO interface standard, Oculink interface standard, Gen-z interface standard, or Swift interface standard, respectively. Correspondingly, the opening position and size of the first hollowed-out area 21 on the intermediate bracket 2 and the second hollowed-out area 131 on the hollowed-out circuit board 13 are adjusted according to the layout of the gold fingers 111 and pads 112 in the adapted interface standard.

[0059] The implementation principle of a high-speed signal transmission circuit board assembly in this application is as follows: a first hollow area 21 penetrating the thickness of the intermediate support 2 is opened, and after assembly, it is closed by the circuit board layers 1 on both sides, thereby forming an air dielectric cavity between the signal interface areas of the two circuit board layers 1. Taking advantage of the characteristic that the dielectric constant of air is close to 1.0 and much lower than that of conventional printed circuit board dielectric materials such as FR-4, the equivalent dielectric constant around the signal interface area is significantly reduced, thereby improving the characteristic impedance of the signal interface area and helping to achieve matching with the characteristic impedance of the signal trace.

[0060] Meanwhile, by transferring the hollowed-out area from the grounding layer inside the circuit board layer 1 to the intermediate support 2 between the two circuit board layers 1, the hollowed-out area of ​​the grounding area can be reduced, thus reducing the problem of loss of electromagnetic shielding between adjacent signal interfaces due to the large-area hollowing out of the grounding area. In this way, by spatially separating the impedance boosting function and the electromagnetic shielding function, the air dielectric cavity undertakes the function of boosting impedance, while the grounding layer inside the circuit board layer 1 retains the function of electromagnetic shielding, thus taking into account the technical effects of impedance matching and signal crosstalk suppression.

[0061] In addition, a shielding part is provided in the third hollow structure 1311. The shielding part introduces a local grounding reference structure in the gold finger 111. It can compensate for the impedance value while maintaining the low dielectric constant of the air medium to improve the characteristic impedance. At the same time, as a grounded electromagnetic isolation barrier, it can effectively absorb and suppress electromagnetic crosstalk of the gold finger 111. While ensuring accurate impedance matching, it improves the signal integrity and anti-interference ability of the gold finger 111.

[0062] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-speed signal transmission circuit board assembly, characterized in that: The assembly includes two circuit board layers (1) arranged opposite to each other and an intermediate support (2) located between the two circuit board layers (1). The stacked structure of the two circuit board layers (1) is symmetrically arranged with respect to the intermediate support (2). Each circuit board layer (1) is provided with a signal interface area and a grounding area. The intermediate support (2) has a first hollow area (21) that penetrates its own thickness. The position of the first hollow area (21) is aligned vertically with the signal interface areas of the two circuit board layers (1), so that after assembly, the first hollow area (21) is closed by the circuit board layers (1) on both sides, thereby forming an air medium cavity between the signal interface areas of the two circuit board layers (1).

2. The high-speed signal transmission circuit board assembly according to claim 1, characterized in that: The signal interface area includes a plurality of gold fingers (111) and a plurality of pads (112). The first hollow area (21) is correspondingly divided into a first hollow structure (211) corresponding to the plurality of gold fingers (111) and a second hollow structure (212) corresponding to the plurality of pads (112).

3. The high-speed signal transmission circuit board assembly according to claim 2, characterized in that: Each of the circuit board layers (1) includes a PCB board (12), a hollowed-out circuit board (13), and a signal circuit board (11) stacked sequentially. The grounding area is disposed on the hollowed-out circuit board (13), and the signal interface area is disposed on the signal circuit board (11). The signal circuit board (11) and the hollowed-out circuit board (13) are disposed on both sides of the PCB board (12). The hollowed-out circuit board (13) is located on the side of the PCB board (12) closer to the intermediate support (2), and the signal circuit board (11) is located on the side of the PCB board (12) away from the intermediate support (2).

4. The high-speed signal transmission circuit board assembly according to claim 3, characterized in that: Each of the hollowed-out circuit boards (13) is provided with a second hollowed-out area (131), the second hollowed-out area (131) including a third hollowed-out structure (1311) corresponding to the gold finger (111) and a fourth hollowed-out structure (1312) corresponding to the pad (112).

5. The high-speed signal transmission circuit board assembly according to claim 4, characterized in that: The second hollowed-out area (131) is through-hole along the thickness direction of the hollowed-out circuit board (13).

6. The high-speed signal transmission circuit board assembly according to claim 4, characterized in that: The third hollowed-out structure (1311) is provided with a shielding part.

7. The high-speed signal transmission circuit board assembly according to claim 6, characterized in that: Each PCB board (12) has a first connection area (121) at the position corresponding to the pad (112), and each PCB board (12) has a second connection area (122) at the position corresponding to the gold finger (111).

8. The high-speed signal transmission circuit board assembly according to claim 3, characterized in that: The intermediate support (2) is provided with at least one column (22) on each of the circuit board layers (1) on both sides. The column (22) is provided with two hollow circuit boards (13), the PCB board (12) and the signal circuit board (11) in sequence.

9. The high-speed signal transmission circuit board assembly according to claim 8, characterized in that: Each column (22) has a block (221) at one end near the signal interface area, and each PCB board (12) has a third connection area (123) at the position corresponding to the block (221). Each signal circuit board (11) is disposed between the corresponding third connection area (123) and the corresponding block (221).

10. The high-speed signal transmission circuit board assembly according to claim 2, characterized in that: It also includes a connecting plate (3) and several wires (4), the intermediate bracket (2) is embedded in the connecting plate (3), and each wire (4) passes through the connecting plate (3) and is welded to the corresponding pad (112).

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