Signal transmission devices and electronic equipment

Abstract

This application provides a signal transmission device and an electronic device, relating to the field of signal transmission. The signal transmission device of this application includes a multilayer wiring structure formed by sequentially alternating metal layers and insulating dielectric layers. The multilayer wiring structure includes a first signal line and a second signal line located in different metal layers. The first signal line is located in a first metal layer, and the second signal line is located in a second metal layer. Multiple metal layers are spaced apart between the first and second metal layers. The first signal line and the second signal line are coupled through a cavity formed in the multilayer wiring structure. The cavity sidewall includes multiple first metal vias, and the multiple first metal vias are located in areas outside the first and second signal lines. Each of the multiple first metal vias is used to connect a metal reference surface in the first metal layer to a metal reference surface in the second metal layer. The signal transmission device of this application can reduce insertion loss when signals pass through layers in a multilayer wiring structure.

Description

Technical Field

[0001] This application relates to the field of signal transmission, and more particularly to a signal transmission device and electronic device. Background Technology

[0002] Currently, high-frequency signals with frequencies above 1 GHz, such as millimeter waves (with frequencies ranging from 30 GHz to 300 GHz), have numerous applications in fields such as mobile communication, positioning and navigation, satellite remote sensing, radio astronomy, and meteorological physics.

[0003] With the rapid development of high-frequency technology, the insertion loss and return loss of high-frequency lines in multilayer wiring structures used for transmitting high-frequency signals play a crucial role in the overall performance of these structures. Especially in some circuit boards, due to layout constraints, high-frequency lines need to be placed in different metal layers, typically using metallized vias to connect them. When a high-frequency signal passes through a metallized via, it easily radiates electromagnetic waves into the surrounding circuit board, diffusing a significant amount of electromagnetic energy and preventing some energy from continuing along the intended transmission direction, resulting in high insertion loss for the metallized via. Furthermore, the impedance matching between the metallized via and the high-frequency lines in the two different metal layers is often poor, leading to significant signal reflection at the connection point, resulting in high return loss. These two factors significantly degrade the circuit board's performance and cause substantial signal transmission distortion. Summary of the Invention

[0004] This application provides a signal transmission device and electronic device that can reduce insertion loss when signals pass through layers in a multilayer wiring structure.

[0005] This application provides a signal transmission device, including a multilayer wiring structure formed by alternating metal layers and insulating dielectric layers; the multilayer wiring structure includes a first signal line and a second signal line located in different metal layers and connected by a coupling cavity; the first signal line is located in a first metal layer, the second signal line is located in a second metal layer, and a plurality of metal layers are spaced apart between the first metal layer and the second metal layer; the first signal line and the second signal line are coupled through a cavity formed in the multilayer wiring structure; the metal sidewall of the cavity includes a plurality of first metal vias; the plurality of first metal vias are disposed in areas other than the first signal line and the second signal line, and the plurality of first metal vias are all used to connect a metal reference surface in the first metal layer and a metal reference surface in the second metal layer.

[0006] The signal transmission device provided in this application embodiment couples two signal lines located on different layers using a cavity (i.e., a coupling cavity). The sidewall of the cavity includes multiple metal vias that connect the metal reference surfaces in the metal layers where the two signal lines are located. This allows the multiple metal vias to form a ground shield on the sidewall of the coupling cavity, reducing the insertion loss of the signal (e.g., millimeter wave signal) when passing through the coupling cavity, thereby reducing the signal loss of the signal transmission device.

[0007] In some possible implementations, a third metal layer and a fourth metal layer are spaced apart between the first metal layer and the second metal layer, with the third metal layer closer to the first metal layer relative to the fourth metal layer. The metal sidewall of the cavity further includes a second metal via. The second metal via is positioned directly opposite the first signal line. The second metal via is used to connect a metal reference surface in the third metal layer and a metal reference surface in the fourth metal layer. In this case, by further providing a second metal via forming the cavity sidewall between the metal reference surfaces of the third and fourth metal layers at the position opposite the first signal line, the gap formed by the first metal via at the position corresponding to the first signal line is filled, further improving the integrity of the cavity sidewall (i.e., the ground shield), greatly enhancing the shielding effect of the coupling cavity, and reducing insertion loss.

[0008] In some possible implementations, the metal sidewall of the cavity further includes a third metal via; the third metal via is disposed directly opposite to the first signal line; the third metal via is used to connect the metal reference surface of the fourth metal layer and the metal reference surface of the second metal layer. In this case, by further providing a second metal via forming the cavity sidewall between the metal reference surfaces of the fourth and second metal layers at the position opposite to the first signal line, the gap located below the second metal via at the position opposite to the first signal line is further filled, further improving the integrity of the cavity sidewall (i.e., the ground shield), greatly enhancing the shielding effect of the coupling cavity, and reducing insertion loss.

[0009] In some possible implementations, the orthographic projection of the third metal via is tangent to the orthographic projection of the second metal via along the thickness direction of the multilayer wiring structure. In this case, when the second and third metal vias are formed by mechanical drilling, damage to the previously formed metal vias can be avoided by setting the second and third metal vias to be staggered and tangential.

[0010] In some possible implementations, the orthographic projection of the third metal via overlaps with the orthographic projection of the second metal via along the thickness direction of the multilayer wiring structure. In this case, laser drilling can be used to form the second and third metal vias; during the fabrication process, the laser energy can be adjusted to ensure that the ends of the second and third metal vias overlap without damaging the previously formed metal vias.

[0011] In some possible implementations, the metal sidewall of the cavity further includes a fourth metal via; the fourth metal via is positioned directly opposite the second signal line; the fourth metal via is used to connect the metal reference surface of the fourth metal layer and the metal reference surface of the third metal layer. In this case, by further providing a fourth metal via forming the cavity sidewall between the metal reference surfaces of the third and fourth metal layers at the position opposite the second signal line to fill the gap formed by the first metal via at the corresponding position of the second signal line, the integrity of the cavity sidewall (i.e., the ground shield) is further improved, the shielding effect of the coupling cavity is enhanced to a greater extent, and the insertion loss is reduced.

[0012] In some possible implementations, the metal sidewall of the cavity further includes a fifth metal via; the fifth metal via is positioned directly opposite the second signal line; the fifth metal via is used to connect the metal reference surface of the third metal layer and the metal reference surface of the first metal layer. In this case, by further providing a second metal via forming the cavity sidewall between the metal reference surfaces of the third metal layer and the first metal layer at the position opposite the second signal line, the gap located above the fourth metal via at the position opposite the second signal line is further filled, thereby further improving the integrity of the cavity sidewall (i.e., the ground shield), greatly enhancing the shielding effect of the coupling cavity, and reducing insertion loss.

[0013] In some possible implementations, the orthographic projection of the fifth metal via is tangent to the orthographic projection of the fourth metal via along the thickness direction of the multilayer wiring structure.

[0014] In this case, when the fifth and fourth metal vias are formed by mechanical drilling, and the fifth and fourth metal vias are set to be staggered and tangential, damage to the previously formed metal vias can be avoided.

[0015] In some possible implementations, the orthographic projections of the fifth metal via and the fourth metal via overlap in the thickness direction of the multilayer wiring structure. In this case, laser drilling can be used to form the fifth and fourth metal vias; during the fabrication process, the laser energy can be adjusted to ensure that the ends of the fifth and fourth metal vias overlap without damaging the previously formed metal vias.

[0016] In some possible implementations, the third metal layer and the first metal layer are two adjacent metal layers, and the insulating dielectric layer between the third metal layer and the first metal layer is a prepreg.

[0017] In some possible implementations, a fifth metal layer is disposed between the third metal layer and the first metal layer; the first metal layer, the fifth metal layer, and the insulating dielectric layer located between the first metal layer and the fifth metal layer are all made of a double-sided copper-clad substrate; the insulating dielectric layer between the third metal layer and the fifth metal layer is a prepreg.

[0018] In some possible implementations, the second metal layer and the fourth metal layer are two adjacent metal layers, and the insulating dielectric layer between the second metal layer and the fourth metal layer is a prepreg.

[0019] In some possible implementations, a sixth metal layer is disposed between the second metal layer and the fourth metal layer; the second metal layer, the sixth metal layer, and the insulating dielectric layer located between the second metal layer and the sixth metal layer are all made of a double-sided copper-clad substrate; the insulating dielectric layer between the fourth metal layer and the sixth metal layer is a prepreg.

[0020] In some possible implementations, the first metal layer, the fifth metal layer, and the insulating dielectric layer located between the first and fifth metal layers are all made of a double-sided copper-clad substrate, and the cavity extends from the location of the fifth metal layer to the region directly opposite the second metal via. This avoids the coupling cavity forming a gap between the second metal via and the upper fifth metal layer, thus preventing radiation leakage problems at this location.

[0021] In some possible implementations, the second metal layer, the sixth metal layer, and the insulating dielectric layer located between the second and sixth metal layers are all made of a double-sided copper-clad substrate, and the cavity extends from the location of the sixth metal layer to the area directly opposite the fourth metal via. This avoids the coupling cavity forming a gap between the fourth metal via and the upper sixth metal layer, thus preventing radiation leakage problems at this location.

[0022] In some possible implementations, the first metal via is a solid metal pillar or a hollow metal pillar.

[0023] In some possible implementations, the second metal via is a solid metal pillar or a hollow metal pillar.

[0024] In some possible implementations, the third metal via is a solid metal pillar or a hollow metal pillar.

[0025] In some possible implementations, the fourth metal via is a solid metal pillar or a hollow metal pillar.

[0026] In some possible implementations, the fifth metal via is a solid metal pillar or a hollow metal pillar.

[0027] In some possible implementations, the metal reference plane in each metal layer is connected to the same reference potential terminal via metal vias disposed in the multilayer wiring structure.

[0028] In some possible implementations, the signal transmission device is provided with metal shielding covers on both sides of the multilayer wiring structure along the thickness direction; the orthographic projection of the metal shielding covers at least covers the orthographic projection of the cavity along the thickness direction of the multilayer wiring structure. In this case, the two metal shielding covers located at both ends of the cavity and the metal vias on the cavity sidewalls together form a more complete ground shield, thereby reducing insertion loss to a greater extent.

[0029] In some possible implementations, both the first signal line and the second signal line include a probe extending into the coupling cavity and a coplanar microstrip transmission line located outside the cavity.

[0030] In some possible implementations, both the first signal line and the second signal line include a probe extending into the cavity and a coplanar microstrip transmission line located outside the cavity; the probe employs a coupling array. In this case, the probe itself can provide some shielding for the coupling cavity, thereby reducing insertion loss.

[0031] In some possible implementations, at least one metal layer between the first metal layer and the second metal layer is provided with a coupling element located within the cavity to improve the signal coupling performance in the coupling cavity.

[0032] This application also provides an electronic device, including a signal transmission device in any of the aforementioned possible implementations. Attached Figure Description

[0033] Figure 1A schematic cross-sectional view of a signal transmission device along the extension direction of a first signal line and a second signal line, provided in an embodiment of this application.

[0034] Figure 2 for Figure 1 A schematic diagram of the structure at the location of the first metal layer;

[0035] Figure 3 for Figure 1 A schematic diagram of the structure at the location of the second metal layer;

[0036] Figure 4 for Figure 1 A schematic diagram of the structure of the intermediate metal layer;

[0037] Figure 5 This is a schematic diagram of the structure of a signal transmission device provided in an embodiment of this application;

[0038] Figure 6 This is a schematic diagram of the structure of a signal transmission device at the location of the first metal layer, provided in an embodiment of this application.

[0039] Figure 7 This is a schematic diagram of the structure of a signal transmission device located at the second metal layer, as provided in an embodiment of this application.

[0040] Figure 8 This is a schematic diagram of the structure of a signal transmission device at the location of the intermediate metal layer, provided in an embodiment of this application.

[0041] Figure 9 This is a schematic diagram of the structure of a signal transmission device at the location of the intermediate metal layer, provided in an embodiment of this application.

[0042] Figure 10 A schematic cross-sectional view of a signal transmission device along the extension direction of a first signal line and a second signal line, provided in an embodiment of this application.

[0043] Figure 11 A schematic cross-sectional view of a signal transmission device along the extension direction of a first signal line and a second signal line, provided in an embodiment of this application.

[0044] Figure 12 A schematic cross-sectional view of a signal transmission device along the extension direction of a first signal line and a second signal line, provided in an embodiment of this application.

[0045] Figure 13a A schematic cross-sectional view of a signal transmission device along the extension direction of a first signal line and a second signal line, provided in an embodiment of this application.

[0046] Figure 13bA schematic cross-sectional view of a signal transmission device along the extension direction of a first signal line and a second signal line, provided in an embodiment of this application.

[0047] Figure 14 A schematic cross-sectional view of a signal transmission device along the extension direction of a first signal line and a second signal line, provided in an embodiment of this application.

[0048] Figure 15 This is a schematic diagram of the structure of a signal transmission device at the location of the intermediate metal layer, provided in an embodiment of this application.

[0049] Figure 16 A scattering parameter curve of a millimeter-wave signal of a signal transmission device provided in an embodiment of this application;

[0050] Figure 17 A scattering parameter curve of a millimeter-wave signal of a signal transmission device provided in an embodiment of this application;

[0051] Figure 18 A scattering parameter curve of a millimeter-wave signal of a signal transmission device provided in an embodiment of this application;

[0052] Figure 19 A scattering parameter curve of a millimeter-wave signal of a signal transmission device provided in an embodiment of this application;

[0053] Figure 20 A scattering parameter curve of a millimeter-wave signal of a signal transmission device provided in an embodiment of this application;

[0054] Figure 21 A scattering parameter curve of a millimeter-wave signal of a signal transmission device provided in an embodiment of this application;

[0055] Figure 22 A scattering parameter curve of a millimeter-wave signal of a signal transmission device provided in an embodiment of this application. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0057] The terms "first," "second," etc., used in the specification, embodiments, claims, and drawings of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or order. Furthermore, "upper," "lower," etc., in the embodiments of this application are used only relative to the orientation of components in the drawings. These directional terms are relative concepts used for relative description and clarification and may vary accordingly depending on the orientation of the components in the drawings. "Comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or apparatus is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0058] This application provides an electronic device that includes a signal transmission device for signal transmission, such as a millimeter-wave signal transmission device. The following embodiments are illustrated using this device as an example.

[0059] In signal transmission devices, through-layer wiring is unavoidable. In the signal transmission device provided in this application embodiment, two signal lines that are set in different layers are connected by cavity coupling (the cavity can also be called a coupling cavity), and the sidewall of the cavity is formed by dispersing multiple metal vias, so that the cavity can act as a ground shield to reduce the through-layer insertion loss of the transmitted signal.

[0060] This application does not impose specific restrictions on the specific configuration of the electronic device; for example, the electronic device can be a millimeter-wave radar, a millimeter-wave sensor, a mobile phone, a computer, etc.

[0061] This application does not impose specific restrictions on the specific configuration of signal transmission devices using through-layer wiring in electronic devices; for example, the signal transmission device can be a printed circuit board (PCB), a flexible printed circuit (FPC), a packaging substrate, etc.

[0062] The following provides a further description of the signal transmission device provided in the embodiments of this application.

[0063] Figure 1 This is a cross-sectional schematic diagram of a multi-layer wiring structure along the extension directions of the first signal line 10 and the second signal line 20. Figure 2 for Figure 1 A schematic diagram of the multilayer wiring structure shown on one side of the first metal layer M1; Figure 3 for Figure 1 The diagram shown illustrates the multilayer wiring structure on one side of the second metal layer M2. Figure 4 for Figure 1 The diagram shows a cross-sectional view of the multilayer wiring structure at the inner layer (IL); similar figures will not be described in detail below.

[0064] like Figure 1 As shown, the signal transmission device provided in this application embodiment includes a multilayer wiring structure formed by alternating metal layers M and insulating dielectric layers S. The multilayer wiring structure includes a first signal line 10 and a second signal line 20 located in different metal layers and coupled together through a cavity 30; wherein the first signal line 10 is located in the first metal layer M1, the second signal line 20 is located in the second metal layer M2, and a plurality of metal layers M (i.e., intermediate metal layers IL) are spaced between the first metal layer M1 and the second metal layer M2.

[0065] It should be noted that this application does not impose specific limitations on the metal material used for the metal layer M. For example, copper, copper alloys, silver, etc., can be used. Different metal layers M can use the same or different metal materials. The following embodiments are all illustrated using copper as an example. In addition, this application does not impose limitations on the material used for the insulating dielectric layer S. For example, polytetrafluoroethylene (PTFE), modified polyphenylene ether (MPPE), etc., can be used. Different insulating dielectric layers S can use the same or different insulating materials.

[0066] Furthermore, those skilled in the art will understand that the cavity 30 described above is a cavity portion formed by hollow areas positioned opposite each other on the first metal layer M1, the second metal layer M2, and the metal layers between the first metal layer M1 and the second metal layer M2; the metal sidewalls of the cavity 30 are formed by metal through holes located around the cavity. The insulating dielectric layer S located between the first metal layer M1 and the second metal layer M2 fills the cavity 30 (i.e., the aforementioned hollow areas); in order to minimize the insertion loss of the coupling cavity, each insulating dielectric layer S can be made of a material with a low damping factor (df).

[0067] In addition, refer to Figure 2 and Figure 3As shown, the first metal layer M1 retains the metal pattern of the probe 11 of the first signal line 10 within the corresponding cutout area; similarly, the second metal layer M2 retains the metal pattern of the probe 21 of the second signal line 20 within the corresponding cutout area. The metal pattern (excluding the signal lines disposed within the metal layer) retained by each metal layer on the periphery of the cavity 30 serves as a metal reference surface to provide a reference potential, such as a ground potential or power supply potential, to the relevant signal lines. The following embodiments of this application use a ground potential as an example for illustrating the metal reference surface. Of course, in some possible implementations, the metal reference surfaces in each metal layer are connected via metal vias disposed in the multilayer wiring structure to connect to the same reference potential terminal (e.g., a ground terminal).

[0068] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the configuration of the metal vias in the metal sidewalls forming the cavity 30 will be described below.

[0069] In this multilayer wiring structure, the metal sidewall of the cavity 30 includes a plurality of first metal vias 1 (see reference) distributed in areas other than the first signal line 10 and the second signal line 20. Figure 4 Each first metal via 1 is connected to the metal reference surface of the first metal layer 10 and the metal reference surface of the second metal layer 20.

[0070] It is understood that the metal via connecting two layers in this application refers to the metal via connecting the two layers and all interlayer structures located between the two layers. For example, regarding the aforementioned first metal via 1 connecting the first metal layer 10 and the second metal layer 20, it can be understood that while the first metal via 1 connects the metal reference surface of the first metal layer 10 and the metal reference surface of the second metal layer 20, it will necessarily penetrate all interlayer structures (including metal layers and insulating dielectric layers) between the metal reference surfaces of the first metal layer 10 and the second metal layer 20. Other metal vias connecting two layers mentioned below similarly indicate that while the metal via connects the two layers, it will penetrate the interlayer structures between the two layers, and will not be elaborated further below.

[0071] It should be noted that this application does not limit the metal material used for the first metal via 1; for example, it can be a copper pillar. Furthermore, the first metal via 1 can be a solid metal pillar (e.g., a solid copper pillar) or a hollow metal pillar (e.g., a copper tube); this application does not impose specific limitations on this. In practice, it can be determined according to the specific manufacturing process. For example, in some possible implementations, the via can be fabricated first, and then the first metal via 1 can be fabricated using an electroplating process within the via. In this case, the first metal via 1 has a hollow structure. Of course, other metal vias mentioned below can have a similar structure to the first metal via 1, and will not be elaborated further below.

[0072] Additionally, refer to Figure 2 As shown, the first signal line 10 includes a probe 11 located inside the cavity 30 and a trace 12 located outside the cavity 30 and connected to the probe 11. In some possible implementations, such as... Figure 2 As shown, a row of metal vias 100 can be provided on both sides of the trace 12 along the extension direction of the trace 12. The depth of the metal vias 100 can be set according to actual needs. For example, the metal vias 100 can connect the metal reference surface in the first metal layer 10 and the metal reference surface below the first metal layer M1, so that the first signal line 10 forms a coplanar microstrip transmission line.

[0073] Similarly, see reference Figure 3 As shown, a row of metal vias 100 can be provided on both sides of the trace 22 of the second signal line 20. The metal reference surface in the second metal layer M2 and the metal reference surface above the second metal layer M2 are connected through the metal vias 100, so that the second signal line 20 forms a coplanar microstrip transmission line.

[0074] It is understood that the coupling of the first signal line 10 and the second signal line 20 through the cavity 30 in this application is based on the broadband electromagnetic conduction of the electromagnetic master mode of the rectangular waveguide TE (transverse electric mode). The parallel open-circuit short microstrip transmission lines are suspended on the upper and lower sides of the coupling cavity (cavity), thereby realizing semi-enclosed capacitive non-contact vertical directional coupling (that is, most of the current on the waveguide wall is transmitted along the vertical via direction, and a very small amount of current is transmitted along the horizontal metal plane).

[0075] In summary, the signal transmission device provided in this application connects two signal lines located on different layers using a cavity (coupling cavity), and the sidewall of the coupling cavity includes multiple metal vias (i.e., first metal vias) connecting the metal reference surfaces in the metal layers where the two signal lines are located. This allows the multiple metal vias to form a ground shield on the sidewall of the coupling cavity, reducing the insertion loss of signals (e.g., millimeter-wave signals) when passing through the coupling cavity, thereby reducing the signal loss of the signal transmission device. Especially for millimeter-wave signal transmission devices, this can effectively improve the overall RF performance of the device.

[0076] Building upon this, to further ensure the shielding effect of the coupling cavity and minimize the insertion loss of millimeter-wave signals, some possible implementation methods include... Figure 5 As shown, metal shielding covers (C1, C2) can be respectively provided on both sides of the multilayer wiring structure of the signal transmission device along the thickness direction DD', and the two metal shielding covers (C1, C2) are respectively connected to the two ends of the metal vias (including but not limited to the first metal via 1) forming the sidewall of the cavity 30; and along the thickness direction DD' of the multilayer wiring structure, the orthographic projection of the two metal shielding covers (C1, C2) at least covers the orthographic projection of the cavity 30, that is, the two metal shielding covers cover the area where the top surface and the ground surface of the cavity 30 are respectively located. In this case, the two metal shielding covers can form a more complete shield with the metal sidewall of the cavity 30, which can play a better shielding role for the coupling cavity, thereby reducing insertion loss to a greater extent.

[0077] Furthermore, this application does not impose specific restrictions on the arrangement of the probes (11, 21) in the signal lines (10, 20). In practice, the shape and size of the probes can be selected as needed. For example, Figure 2 As shown, the probe 11 in the first signal line 10 can adopt a slender structure with the same or similar width as the trace 12; for example, as Figure 6 As shown, the probe 11 in the first signal line 10 can adopt a coupled pad structure, that is, the probe 11 is a planar structure. Similarly, as Figure 3 and Figure 7 As shown, the probe 21 in the second signal line 20 can be a slender structure with the same or similar width as the trace 22, or it can be a pad structure.

[0078] Compared to the elongated structure of probes (11, 21) in signal lines (10, 20), the use of a pad-coupled array structure (11, 21) allows the probes themselves to provide some shielding for the coupling cavity. In other words, under the same conditions, probes with a pad-coupled array structure can significantly reduce signal insertion loss compared to those with an elongated structure. Therefore, in some possible implementations, with a pad-coupled array structure probe, a metal shielding cover may not be required on the side of the probe where the coupling cavity is located.

[0079] Based on this, in some possible implementation methods, such as Figure 8 As shown, one or more intermediate metal layers IL between the first metal layer M1 and the second metal layer M2 can be arranged inside the cavity 30 as a coupling element P (pad) to improve the signal coupling performance in the coupling cavity.

[0080] In addition, regarding the fabrication of the first metal via 1 in the aforementioned multilayer wiring structure, in some possible implementations, the first metal layer M1, the second metal layer M2, and all other interlayers between the first metal layer M1 and the second metal layer M2 can be laminated together (i.e., a single lamination is sufficient). Then, a through hole is fabricated at the sidewall position of the corresponding cavity 30, and copper is plated in the through hole to form the first metal via 1 of a copper tube structure. In this case, the first metal via 1 penetrates the metal reference surface in the first metal layer M1 and the metal reference surface in the second metal layer M2, and serves as the metal sidewall of the cavity.

[0081] Understandably, reference Figure 4 As shown, when creating the through hole to be formed as the first metal via 1 on the side wall of the cavity 30, at the position directly opposite the first signal line 10 and the second signal line 20 (refer to...) Figure 2 and Figure 3 Due to the obstruction of the first signal line 10 and the second signal line 20, a through hole cannot be formed at this position. That is, a through hole can only be formed in the side wall area of ​​the cavity 30 outside the area of ​​the first signal line 10 and the second signal line 20, thereby forming the first metal via 1. As a result, the ground shield formed by multiple first metal vias 1 will form a gap at the position of the first signal line 10 and the second signal line 20, and a relatively obvious radiation loss is likely to occur at the gap position.

[0082] Based on this, in order to further improve the integrity of the metal sidewalls of cavity 30, enhance the shielding effect of the coupling cavity, and reduce insertion loss; in some possible implementation methods, refer to Figure 9As shown, the metal sidewall of cavity 30 may also include a metal via (such as 2) disposed opposite to the first signal line 10, and the metal via is connected to a metal reference surface in at least one metal layer located on the side of the first metal layer M1 near the second metal layer M2, so as to fill the gap formed by the first metal via 1 at the position corresponding to the first signal line 20, thereby reducing radiation loss, improving the integrity of the cavity sidewall (i.e., ground shield), further improving the shielding effect of the coupling cavity, and reducing insertion loss.

[0083] It should be noted that the aforementioned "metal via disposed directly opposite to the first signal line 10" means that the metal via and the orthographic projection of the first signal line 10 in the thickness direction DD' of the multilayer wiring structure have an overlapping area. For example, the orthographic projection of the first signal line 10 may cover the orthographic projection of the metal via. The terms "disposed directly opposite" and "directly opposite" as used below can be understood in this way, and will not be elaborated further below.

[0084] Similarly, see reference Figure 9 As shown, the metal sidewall of cavity 30 may also include a metal via (such as 4) disposed opposite to the second signal line 20, and the metal via is connected to a metal reference surface in at least one metal layer located on the side of the second metal layer M2 near the first metal layer M1, so as to fill the gap formed by the first metal via 1 at the position corresponding to the second signal line 20, thereby reducing radiation loss, improving the integrity of the cavity sidewall (i.e., ground shield), further improving the shielding effect of the coupling cavity, and reducing insertion loss.

[0085] It should be noted that the position directly opposite the first signal line 10 may include one or more metal vias, such as two; this application does not impose specific limitations on this, and in practice, the length, number, and thickness of the metal vias at the position directly opposite the first signal line 10 can be set according to the specific configuration of the first signal line 10. Similarly, a metal via can be provided at the position directly opposite the second signal line 20.

[0086] The following example, taking the case where the first signal line 10 and the second signal line 20 are located on different sides of the cavity 30, will be used to further explain the metal vias that are positioned opposite each other.

[0087] It should be noted here that, for the first signal line 10 and the second signal line 20 being located on different sides of the cavity 30, it is understood that, along the thickness direction DD' of the multilayer wiring structure, the orthographic projections of the first signal line 10 and the second signal line 20 do not coincide, and the included angle between them is not zero; for example, the included angle between them can be 45°, 135°, or 180° (e.g., ...). Figure 1 The following description uses 180° as an example to illustrate the metal vias positioned opposite each other for the first signal line 10 and the second signal line 20.

[0088] like Figure 10 and Figure 11 As shown, a third metal layer M3 and a fourth metal layer M4 are disposed between the first metal layer M1 and the second metal layer M2, with a gap between them. The third metal layer M3 is closer to the first metal layer M1 than the fourth metal layer M4.

[0089] For a metal via positioned directly opposite the first signal line 10:

[0090] In some possible ways of implementation, such as Figure 10 and Figure 11 As shown, the metal sidewall of cavity 30 may be provided with a second metal via 2 at a position directly opposite to the first signal line 10. The second metal via 2 connects the metal reference surface in the third metal layer M3 and the metal reference surface in the fourth metal layer M4.

[0091] Building upon this, to further fill the gap located below the second metal via 2, directly opposite the first signal line 10, and to further reduce radiation loss, some possible implementation methods include... Figure 10 and Figure 11 As shown, a third metal via 3 is provided on the metal sidewall of cavity 30 at the position directly opposite the first signal line 10. The third metal via 3 connects the metal reference surface in the fourth metal layer M4 and the metal reference surface in the second metal layer M2. This maximizes the filling of the gap formed by the first metal via 1 at the position corresponding to the first signal line 10, effectively improving the integrity of the cavity sidewall (i.e., the ground shield) at the position corresponding to the first signal line 10, further improving the shielding effect of the coupling cavity, and reducing insertion loss.

[0092] In this application, the relative positions of the second metal via 2 and the third metal via 3 along the thickness direction DD' perpendicular to the multilayer wiring structure are not specifically limited, and can be selected according to process requirements in practice. The thickness direction DD' mentioned below can be referred to as... Figure 5 The directions shown in the figure are not shown in other figures for the purpose of simplification.

[0093] For example, in some possible implementations, the orthographic projections of the second metal via 2 and the third metal via 3 can be tangent to each other along the thickness direction DD' (i.e., the planar direction of the metal layer extension) of the multilayer wiring structure. That is, the two adjacent ends of the second metal via 2 and the third metal via 3 are staggered and tangent. Of course, it is understandable that there may be process errors in actual manufacturing, and there may be appropriate gaps or overlaps between the two adjacent ends of the second metal via 2 and the third metal via 3.

[0094] For example, in some possible implementations, the orthographic projections of the second metal via 2 and the third metal via 3 may have overlapping regions along the thickness direction DD' (i.e., the plane direction in which the metal layers extend) of the vertical multilayer wiring structure. These regions may be completely overlapping or partially overlapping, meaning that the two adjacent ends of the second metal via 2 and the third metal via 3 have overlapping regions.

[0095] For example, in some possible implementations, the orthographic projections of the second metal via 2 and the third metal via 3 can be set alternately along the thickness direction DD' of the vertical multilayer wiring structure (the interval should be minimized as much as possible to consider the shielding effect).

[0096] For metal vias positioned directly opposite the second signal line 20:

[0097] In some possible ways of implementation, such as Figure 10 and Figure 11 As shown, the metal sidewall of cavity 30 may be provided with a fourth metal via 4 at a position directly opposite to the second signal line 20. The fourth metal via 4 connects the metal reference surface in the third metal layer M3 and the metal reference surface in the fourth metal layer M4.

[0098] Based on this, in order to further fill the gap above the fourth metal via 4 at the corresponding second signal line 20 position and further reduce radiation loss, in some possible ways, such as Figure 10 and Figure 11 As shown, the metal sidewall of cavity 30 can also be provided with a fifth metal via 5 at the position directly opposite the second signal line 20. The fifth metal via 5 connects the metal reference surface in the third metal layer M3 and the metal reference surface in the first metal layer M1. This maximizes the filling of the gap formed by the first metal via 1 at the position corresponding to the second signal line 20, effectively improving the integrity of the cavity sidewall (i.e., the ground shield) at the position corresponding to the second signal line 20, further improving the shielding effect of the coupling cavity, and reducing insertion loss.

[0099] In this application, there are no special restrictions on the relative positions of the fourth metal via 4 and the fifth metal via 5 along the thickness direction DD' of the multilayer wiring structure. In practice, they can be selected and set according to process requirements. For details, please refer to the above description of the relative positions of the second metal via 2 and the third metal via 3 along the thickness direction DD' of the multilayer wiring structure. It will not be repeated here.

[0100] It should be noted that, in order to maximize the integrity and shielding effect of the metal sidewalls of cavity 30, some possible implementation methods include... Figure 10 or Figure 11As shown, the metal sidewall of cavity 30 can be provided with metal vias at positions directly opposite the first signal line 10 and the second signal line 20; for example, as Figure 10 , Figure 11 As shown, the aforementioned second metal via 2, third metal via 3, fourth metal via 4, and fifth metal via 5 can be provided simultaneously; for illustration purposes, please refer to... Figure 9 A cross-sectional view of the intermediate metal layer IL (M3, M4 or the metal layer between M3 and M4).

[0101] In addition, considering the actual production process, such as Figure 10 and Figure 11 As shown, in some possible implementations, the second metal via 2 and the fourth metal via 4 can both penetrate the metal reference surfaces of the third metal layer M3 and the fourth metal layer M4. The third metal via 3 penetrates the second metal layer M2 and the insulating dielectric layer S that contacts the fourth metal layer M4 and is closer to the second metal layer M2. The fifth metal via 5 penetrates the first metal layer M1 and the insulating dielectric layer S that contacts the third metal layer M3 and is closer to the first metal layer M1.

[0102] In this case, during actual fabrication, the third metal layer M3, the fourth metal layer M4 forming the signal transmission device, and the interlayer structure between the third metal layer M3 and the fourth metal layer M4 can be pressed together first. After pressing, through holes are formed at the positions on the sidewall of the cavity 30 corresponding to the positions where the first signal line 10 and the second signal line 20 are to be formed, and copper pillars (i.e., 2 and 4) are formed in the through holes. Then, the first metal layer M1, the second metal layer M2, and the related insulating dielectric layer S of the signal transmission device are pressed together again on the outside of the third metal layer M3 and the fourth metal layer M4. After the second pressing, blind via holes are formed at the positions corresponding to the second metal via 2 and the fourth metal via 4, and copper pillars (i.e., 3 and 5) are formed in the blind via holes. Of course, at the same time as forming the blind via holes, through holes penetrating the metal reference surface in the first metal layer M1 and the metal reference surface in the second metal layer M2 can be formed in the area outside the first signal line 10 and the second signal line 20, and copper pillars (i.e., 1) are formed in the through holes. Of course, depending on actual needs, the aforementioned metal via 100 can also be formed at this time. It can be understood here that after the secondary lamination, for the multilayer wiring structure, the second metal via 2 and the fourth metal via 4 are equivalent to being buried via holes.

[0103] Regarding the blind holes formed at the positions corresponding to the second metal via 2 and the fourth metal via 4 after the second lamination:

[0104] In some possible implementation methods, blind holes can be formed by mechanical drilling. In this case, in order to avoid damage to the metal vias below (i.e., 2 and 4) caused by mechanical drilling, the blind holes can be designed to be staggered and tangent to the metal vias below (i.e., 2 and 4). That is, the two adjacent ends of the second metal via 2 and the third metal via 2 are staggered and tangent (of course, considering process errors, a certain deviation is allowed). The two adjacent ends of the fourth metal via 4 and the fifth metal via 5 are staggered and tangent.

[0105] In some possible implementations, blind vias (e.g., laser-drilled vias) can be formed using laser drilling. In this case, the laser energy can be adjusted to ensure that the underlying metal vias (i.e., 2 and 4) are not damaged during the formation of the blind via. Thus, the blind vias can be designed to be directly opposite the underlying metal vias (i.e., 2 and 4). That is, there can be an overlapping area between the two adjacent ends of the second and third metal vias 2 (they can overlap or partially overlap), and there can be an overlapping area between the two adjacent ends of the fourth and fifth metal vias 4 and 5. Of course, when forming blind vias using laser drilling, the vias can be formed separately using etching processes at the metal layer location.

[0106] In addition, the following section will further explain the relevant settings of the third metal via 3 and the fifth metal via 5, based on the specific interlayer setup structure (M1, M2, M3, M4).

[0107] Regarding the setting of the fifth metal via 5:

[0108] like Figure 10 As shown, in some possible implementations, the third metal layer M3 and the first metal layer M1 are two adjacent metal layers, and the insulating dielectric layer S between the third metal layer M3 and the first metal layer M1 is a prepreg PP1; in this case, the fifth metal via 5 can penetrate the metal reference surface in the first metal layer M1 and the prepreg PP1, and connect with the metal reference surface in the third metal layer M3.

[0109] As illustrated, during the manufacturing process, after forming the second metal via 2 and the fourth metal via 4 that penetrate the third metal layer M3 and the fourth metal layer M4, the first metal layer M1 (which can be a single-layer copper sheet structure) is pressed onto the upper surface of the third metal layer M3 through the prepreg PP1, and then a blind hole is formed that penetrates the first metal layer M1 and the prepreg PP1, and a copper pillar (i.e., the fifth metal via 5) is formed in the blind hole.

[0110] like Figure 11As shown, in some possible implementations, a fifth metal layer M5 is disposed between the third metal layer M3 and the first metal layer M1; the first metal layer M1, the fifth metal layer M5, and the insulating dielectric layer located between the first metal layer M1 and the fifth metal layer M5 are all made of a double-sided copper clad substrate (core) CR1; the insulating dielectric layer between the third metal layer M3 and the fifth metal layer M5 is a prepreg PP3; in this case, the fifth metal via 5 can penetrate the double-sided copper clad substrate CR1 and the prepreg PP3, and connect with the metal reference surface in the third metal layer M3.

[0111] As illustrated, during the manufacturing process, after forming the second metal via 2 and the fourth metal via 4 that penetrate the third metal layer M3 and the fourth metal layer M4, a double-sided copper-clad substrate CR1 is laminated onto the upper surface of the third metal layer M3 using a prepreg PP3. Then, blind holes are formed that penetrate the double-sided copper-clad substrate CR1 and the prepreg PP3, and copper pillars (i.e., the fourth sub-metal via L4) are formed in the blind holes.

[0112] Regarding the setting of the third metal via 3:

[0113] like Figure 10 As shown, in some possible implementations, the second metal layer M2 and the fourth metal layer M4 are two adjacent metal layers, and the insulating dielectric layer between the second metal layer M2 and the fourth metal layer M4 is a prepreg PP2; in this case, the third metal via 3 can penetrate the metal reference surface in the second metal layer M2 and the prepreg PP2, and connect with the metal reference surface in the fourth metal layer M4.

[0114] As illustrated, during the manufacturing process, after forming the second metal via 2 and the fourth metal via 4 that penetrate the third metal layer M3 and the fourth metal layer M4, the second metal layer M2 (which can be a single-layer copper sheet structure) is pressed onto the lower surface of the fourth metal layer M4 through the prepreg PP2, and then a blind hole is formed that penetrates the second metal layer M2 and the prepreg PP2, and a copper pillar (i.e., the third metal via 3) is formed in the blind hole.

[0115] like Figure 11 As shown, in some possible implementations, a sixth metal layer M6 is disposed between the second metal layer M2 and the fourth metal layer M4; the second metal layer M2, the sixth metal layer M6, and the insulating dielectric layer located between the second metal layer M2 and the sixth metal layer M6 are all made of a double-sided copper-clad substrate CR2; the insulating dielectric layer between the fourth metal layer M4 and the sixth metal layer M6 is a prepreg PP4; in this case, the third metal via 3 can penetrate the metal reference surface in the metal layers on both sides of the double-sided copper-clad substrate CR2 and the prepreg PP4, and connect with the metal reference surface in the fourth metal layer M4.

[0116] As illustrated, during the fabrication process, after forming the second metal via 2 and the fourth metal via 4 that penetrate the third metal layer M3 and the fourth metal layer M4, the double-sided copper-clad substrate CR2 can be laminated onto the lower surface of the fourth metal layer M4 through the prepreg PP4. Then, blind holes are formed that penetrate the double-sided copper-clad substrate CR2 and the prepreg PP4, and copper pillars (i.e., the third metal via 3) are formed in the blind holes.

[0117] It should be noted that this application does not impose any special restrictions on the configuration of the third metal layer M3, the fourth metal layer M4, and the interlayer structures between them. For example, multiple double-sided copper-clad substrates can be laminated using prepregs; of course, some metal layers can also be single-layer metal layers (such as copper foil) laminated using prepregs.

[0118] Additionally, refer to Figure 11 As shown, when the first metal layer M1, the fifth metal layer M5, and the insulating dielectric layer between the first metal layer M1 and the fifth metal layer M5 are all made of a double-sided copper-clad substrate CR1, if the cavity 30 formed in the fifth metal layer M5 and the third metal layer M3 has the same size, it will cause a gap m to form between the coupling cavity and the second metal via 2 and the fifth metal layer M5, and radiation leakage is likely to occur at the gap m. Similarly, a gap m will also form in the cavity 30 between the fourth metal via 4 and the sixth metal layer M6, which will also cause radiation leakage.

[0119] Based on this, such as Figure 12 As shown, in some possible implementations, the cavity 30 can be set in the area where the fifth metal layer M5 extends to the area directly opposite the second metal via 2. That is, the area of ​​the fifth metal layer M5 above the second metal via 2 is a cutout area D1 (of course, the specific size of the cutout area D1 can be set according to actual needs). The cutout area D1 itself serves as part of the coupling cavity, thereby avoiding the formation of a gap between the second metal via 2 and the upper fifth metal layer M5, thus avoiding the radiation leakage problem at this point.

[0120] It can be understood that since the area of ​​the fifth metal layer M5 above the second metal via 2 is a cutout area D1, the reference for the first signal line 10 in this cutout area D1 is the metal reference surface in the third metal layer M3, while in areas outside the cutout area D1, the metal reference surface in the fifth metal layer M5 is used as the reference layer. Therefore, in practice, the structure where the area of ​​the fifth metal layer M5 above the second metal via 2 is a cutout area D1 is equivalent to changing the reference layer of the first signal line 10 at the location of the second metal via 2, transitioning the reference layer from the metal reference surface in the fifth metal layer M5 to the metal reference surface in the third metal layer M3. Furthermore, the width of the first signal line 10 can be adjusted accordingly at the location of the reference layer change, depending on actual needs.

[0121] Similarly, see reference Figure 12 As shown, when the second metal layer M2, the sixth metal layer M6, and the insulating dielectric layer between the second metal layer M2 and the sixth metal layer M6 are all made of a double-sided copper-clad substrate CR2, a cavity 30 can be provided in the area where the sixth metal layer M6 extends to the area directly opposite the fourth metal via 4; that is, the area of ​​the sixth metal layer M6 below the fourth metal via 4 is a cutout area D2 (the specific size of the cutout area D2 can be set according to actual needs). In this case, the reference layer of the second signal line 20 in the cutout area D2 is the metal reference surface in the fourth metal layer M4, while in the area outside the cutout area D2, the metal reference surface in the sixth metal layer M6 is used as the reference layer. That is, the second signal line 20 changes the reference layer at the position corresponding to the fourth metal via 4, transitioning from the metal reference surface in the sixth metal layer M6 to the metal reference surface in the fourth metal layer M4. The width of the second signal line 20 can be adjusted at the transition position of the reference layer according to actual needs. In this case, the cutout area D2 of the sixth metal layer M6 itself becomes part of the cavity 30, thus preventing radiation leakage at this location. The width of the second signal line 20 can be adjusted at the transition position of the reference layer as needed.

[0122] It should be noted that, Figure 10 , Figure 11 , Figure 12 The following description uses the same arrangement structure between the first metal layer M1 and the third metal layer M3, and between the second metal layer M2 and the fourth metal layer M4 (e.g., both using copper-clad substrates or a single copper foil laminated together with a prepreg), but this application is not limited to this. In other possible implementations, different arrangement structures can be used between the first metal layer M1 and the third metal layer M3, and between the second metal layer M2 and the fourth metal layer M4; for example, ... Figure 13a , Figure 13b As shown, the first metal layer M1 is a copper-clad substrate CR1, which is pressed onto the upper surface of the third metal layer M3 by a prepreg PP3. The second metal layer M2 is a single metal layer (e.g., copper foil), which is pressed onto the lower surface of the fourth metal layer M4 by a prepreg PP2.

[0123] It should be understood that when a signal transmission device has metal shielding covers on both sides (i.e., the top and bottom sides) in the thickness direction DD' of the multilayer wiring structure, the lower end of the third metal via 3 can be connected to the metal shielding cover located on the lower side of the multilayer wiring structure. Similarly, the upper end of the fifth metal via 5 can be connected to the metal shielding cover located on the upper side of the multilayer wiring structure to improve the integrity of the ground shield.

[0124] In addition, such as Figure 14 and Figure 15 As shown, when the first signal line 10 and the second signal line 20 are located on the same side of the cavity 30 and are arranged opposite each other, in the multilayer wiring structure of this signal transmission device, the metal sidewall of the cavity 30 can be provided with a metal via 6 at the relative position of the first signal line 10 and the second signal line 20. The metal via 6 can connect the metal reference surfaces of the two metal layers (e.g., M3 and M4) located between the first metal layer M1 and the second metal layer M2. Of course, the positions of the two metal layers may vary depending on the actual interlayer arrangement structure. For details, please refer to the aforementioned information. Figure 10 , Figure 11 , Figure 12 The relevant descriptions will not be repeated here.

[0125] Additionally, it should be noted that the embodiments in this application are illustrative examples illustrating the first metal layer M1 and the second metal layer M2 being located at the top and bottom layers of a multilayer wiring structure, respectively; however, this application is not limited to this. The first metal layer M1 and the second metal layer M2 can also be located in the inner layers, for example, referring to... Figure 13a As shown, the first metal layer M1 can be located in the metal layer on the underside of the double-sided copper-clad substrate CR1.

[0126] Furthermore, to ensure the ground shield formed by the multiple metal vias (such as 1, 2, 3, 4, and 5) that form the sidewalls of cavity 30 has a good shielding effect, the distance between adjacent metal vias (1, 2, 3, 4, and 5) should be minimized as much as possible during the actual fabrication of these vias (the smaller the distance, the better the shielding effect). Within the limits allowed by the manufacturing process, the distance between two adjacent metal vias can be set to the minimum. For example, in some possible implementations, the distance between the edges of two adjacent metal vias can be set to 8 mil, 10 mil, 12 mil, etc.

[0127] Compared to the conventional metal via-layer connection used in related technologies for millimeter-wave signals, the insertion loss of millimeter-wave signals in the 76GHz-79GHz frequency band is typically at least 5dB. The insertion loss of the signal transmission device provided in this application embodiment is significantly reduced (below 3dB) in this operating frequency band. The following is a detailed explanation based on the coupling simulation results of various signal transmission devices with different structures in the 76GHz-79GHz millimeter-wave signal in the embodiments of this application.

[0128] Figure 16 To adopt Figure 1The simulation results for the millimeter-wave scattering parameter curve S(1,1), the millimeter-wave scattering parameter curve S(2,2), and the insertion loss coefficient curve S(2,1) of the first signal line 10, the second signal line 20, and the millimeter-wave signal, are shown in the diagram, using the signal transmission device shown (i.e., the cavity 30 without a metal via at the position directly opposite the signal line). It can be seen that the insertion loss of this signal transmission device at 74GHz, 75.3GHz, and 77GHz is 3.57dB, 2.58dB, and 3.27dB, respectively. The average insertion loss of this signal transmission device in the 76GHz-79GHz frequency band is approximately 3dB, which is significantly lower than the 5dB in related technologies.

[0129] Figure 17 To adopt Figure 10 The diagram shows a multi-layer wiring structure (i.e., a metal via is provided in the cavity 30 at the position directly opposite the signal line), and with metal shielding covers provided at both ends of the cavity 30. Simulation results show the millimeter-wave scattering parameter curve S(1,1) for the first signal line 10, the millimeter-wave scattering parameter curve S(2,2) for the second signal line 20, and the insertion loss coefficient curve S(2,1) for the millimeter-wave signal. It can be seen that the insertion loss of this signal transmission device at 76GHz, 77GHz, and 79GHz is 0.66dB, 0.62dB, and 0.58dB, respectively, and the average insertion loss of this signal transmission device in the 76GHz-79GHz frequency band is less than 0.7dB.

[0130] Figure 18 To adopt Figure 10 The diagram shows a multi-layer wiring structure (i.e., a metal via in cavity 30 directly opposite the signal line). However, without metal shielding covers at both ends of cavity 30, the simulation yields the millimeter-wave scattering parameter curve S(1,1) for the first signal line 10, the millimeter-wave scattering parameter curve S(2,2) for the second signal line 20, and the insertion loss coefficient curve S(2,1) for the millimeter-wave signal. It can be seen that the insertion loss of this signal transmission device at 76GHz, 77GHz, and 79GHz is 0.91dB, 0.81dB, and 0.88dB, respectively, and the insertion loss of this signal transmission device in the 76GHz-79GHz frequency band is approximately 0.9dB.

[0131] for Figure 16 and Figure 17 , Figure 18 The results show that by adding a metal via in the cavity 30 at the position opposite the signal line, a more complete ground shield can be formed, which greatly reduces the insertion loss of the millimeter wave signal, thereby significantly reducing the loss of the radio frequency signal and effectively improving the radio frequency performance of the device.

[0132] contrast Figure 17 and Figure 18 The results show that, compared with the insertion loss (below 0.9dB) when no metal shielding covers are provided at both ends of the cavity 30, the insertion loss (below 0.7dB) is reduced when metal shielding covers are provided at both ends of the cavity 30. This demonstrates that by providing metal shielding covers, the shielding effect of the ground shield can be further improved and the insertion loss reduced.

[0133] Figure 19 To adopt Figure 13a The multi-layer wiring structure shown (i.e., employing reference layer replacement technology) has metal shielding covers at both ends of the cavity 30. Simulations yielded the millimeter-wave scattering parameter curves S(1,1) for the first signal line 10, S(2,2) for the second signal line 20, and the insertion loss coefficient curve S(2,1) for the millimeter-wave signal. Figure 19 It can be seen that the insertion loss of the signal transmission device is 0.65dB and 0.75dB at 76GHz and 79GHz, respectively, and the insertion loss of the signal transmission device in the 76GHz-79GHz frequency band is about 0.7dB.

[0134] Figure 20 To adopt Figure 13b The multi-layer wiring structure shown (i.e., without reference layer replacement technology) has metal shielding covers at both ends of the cavity 30. Simulations yielded the millimeter-wave scattering parameter curves S(1,1) for the first signal line 10, S(2,2) for the second signal line 20, and the insertion loss coefficient curve S(2,1) for the millimeter-wave signal. Figure 20 It can be seen that, with the metal shielding cover installed, the insertion loss of the signal transmission device at 76GHz and 79GHz is 1.06dB and 1.07dB respectively, and the insertion loss of the signal transmission device in the 76GHz-79GHz frequency band is about 1.0dB.

[0135] Figure 21 To adopt Figure 13a The multi-layer wiring structure shown (i.e., employing reference layer replacement technology) has no metal shielding caps at both ends of the cavity 30. Simulations yielded the millimeter-wave scattering parameter curves S(1,1) for the first signal line 10, S(2,2) for the second signal line 20, and the insertion loss coefficient curve S(2,1) for the millimeter-wave signal. Figure 21 It can be seen that, with the metal shielding cover installed, the insertion loss of the signal transmission device at 76GHz and 79GHz is 0.86dB and 0.95dB, respectively, and the insertion loss of the signal transmission device in the 76GHz-79GHz frequency band is about 0.9dB.

[0136] Figure 22 To adopt Figure 13bThe multi-layer wiring structure shown (i.e., without reference layer replacement technology) does not have metal shielding covers at both ends of the cavity 30. Simulation results show the millimeter-wave scattering parameter curve S(1,1) for the first signal line 10, the millimeter-wave scattering parameter curve S(2,2) for the second signal line 20, and the insertion loss coefficient curve S(2,1) for the millimeter-wave signal. Figure 22 It can be seen that the insertion loss of the signal transmission device is 1.43dB and 1.38dB at 76GHz and 79GHz, respectively, and the insertion loss of the signal transmission device in the 76GHz-79GHz frequency band is about 1.4dB.

[0137] By comparison Figure 19 and Figure 21 and comparison Figure 20 and Figure 22 It can be seen that, when using the same multi-layer wiring structure, adding a metal shielding cover can further reduce the insertion loss of millimeter-wave signals.

[0138] By comparison Figure 19 and Figure 20 and comparison Figure 21 and Figure 22 It can be seen that, when using the same multi-layer cabling structure, compared with not using the reference layer replacement technology, the reference layer replacement technology can further reduce the insertion loss of millimeter-wave signals.

[0139] In addition, such as Figures 16 to 22 The millimeter-wave scattering parameter curves S(1,1) of the first signal line 10 and S(2,2) of the second signal line 20 show that in the 76GHz-79GHz frequency band, the scattering coefficient of millimeter waves is generally below -10dB, which can effectively ensure the impedance continuity of millimeter-wave signals and the low reflection loss of millimeter-wave signals.

[0140] It should be noted that the aforementioned simulation is only an illustrative example using the 76GHz-79GHz frequency band. This application does not impose specific restrictions on the actual application frequency band of the signal transmission device. In practice, the application frequency band of the signal transmission device can be selected and set as needed.

[0141] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A signal transmission device, characterized in that, This includes a multi-layer wiring structure formed by alternating metal layers and insulating dielectric layers; The multilayer wiring structure includes a first signal line and a second signal line located in different metal layers; the first signal line is located in the first metal layer, the second signal line is located in the second metal layer, and multiple metal layers are disposed between the first metal layer and the second metal layer. The first signal line and the second signal line are coupled through a cavity formed in the multilayer wiring structure; The metal sidewall of the cavity includes a plurality of first metal through holes; Multiple first metal vias are disposed in areas other than the first signal line and the second signal line, and multiple first metal vias are used to connect the metal reference surface in the first metal layer and the metal reference surface in the second metal layer; A third metal layer and a fourth metal layer are disposed between the first metal layer and the second metal layer, with the third metal layer being closer to the first metal layer than the fourth metal layer. The metal sidewall of the cavity further includes: a third metal via; the third metal via is positioned directly opposite the first signal line; The third metal via is used to connect the metal reference surface of the fourth metal layer with the metal reference surface of the second metal layer.

2. The signal transmission device according to claim 1, characterized in that, The metal sidewall of the cavity further includes: a second metal via; the second metal via is disposed directly opposite to the first signal line; The second metal via is used to connect the metal reference surface in the third metal layer and the metal reference surface in the fourth metal layer.

3. The signal transmission device according to claim 2, characterized in that, Along the thickness direction of the multilayer wiring structure, the orthographic projection of the third metal via is tangent to or overlaps with the orthographic projection of the second metal via.

4. The signal transmission device according to claim 2, characterized in that, The metal sidewall of the cavity further includes: a fourth metal via; the fourth metal via is positioned directly opposite the second signal line; The fourth metal via is used to connect the metal reference surface of the fourth metal layer with the metal reference surface of the third metal layer.

5. The signal transmission device according to claim 4, characterized in that, The metal sidewall of the cavity further includes: a fifth metal via; the fifth metal via is positioned directly opposite the second signal line; The fifth metal via is used to connect the metal reference surface of the third metal layer with the metal reference surface of the first metal layer.

6. The signal transmission device according to claim 5, characterized in that, Along the thickness direction of the multilayer wiring structure, the orthographic projection of the fifth metal via is tangent to or overlaps with the orthographic projection of the fourth metal via.

7. The signal transmission device according to any one of claims 2, 3, and 6, characterized in that, The second metal layer and the fourth metal layer are two adjacent metal layers, and the insulating dielectric layer between the second metal layer and the fourth metal layer is a prepreg. Alternatively, a sixth metal layer may be disposed between the second metal layer and the fourth metal layer; the second metal layer, the sixth metal layer, and the insulating dielectric layer located between the second metal layer and the sixth metal layer are all made of a double-sided copper-clad substrate; the insulating dielectric layer between the fourth metal layer and the sixth metal layer is a prepreg. The third metal layer and the first metal layer are two adjacent metal layers, and the insulating dielectric layer between the third metal layer and the first metal layer is a prepreg. Alternatively, a fifth metal layer may be disposed between the third metal layer and the first metal layer; the first metal layer, the fifth metal layer, and the insulating dielectric layer located between the first metal layer and the fifth metal layer may be constructed using a double-sided copper-clad substrate; and the insulating dielectric layer between the third metal layer and the fifth metal layer may be a prepreg.

8. The signal transmission device according to claim 7, characterized in that, The cavity extends from the location of the fifth metal layer to the area directly opposite the second metal via; The cavity extends from the location of the sixth metal layer to the area directly opposite the fourth metal via.

9. The signal transmission device according to any one of claims 1-3, 6, and 8, characterized in that, The signal transmission device is provided with metal shielding covers on both sides of the multilayer wiring structure along the thickness direction. Along the thickness direction of the multilayer wiring structure, the orthographic projection of the metal shielding cover at least covers the orthographic projection of the cavity.

10. The signal transmission device according to any one of claims 1-3, 6, and 8, characterized in that, Both the first signal line and the second signal line include a probe extending into the cavity and a coplanar microstrip transmission line located outside the cavity; the probe is a coupling array.

11. The signal transmission device according to any one of claims 1-3, 6, and 8, characterized in that, At least one metal layer between the first metal layer and the second metal layer is provided with a coupling element located within the cavity.

12. An electronic device, characterized in that, Includes the signal transmission device as described in any one of claims 1-11.

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