High-speed signal transmission structure based on stacked cavities, circuit and electronic device

Abstract

The application discloses a high-speed signal transmission structure based on a stacked cavity, a circuit and electronic equipment, which respectively sets a metal layer, a through metal structure and a cavity for each layer structure on a substrate arranged in multiple layers, and arranges a signal path in the cavity, and provides a structural design scheme for reducing the insertion loss value and return loss value in the high-speed signal transmission process. The application forms a 3D shielding system surrounding the cavity through the metal layer and the through metal structure, and can significantly reduce signal transmission loss in cooperation with the hollow cavity. Compared with the existing packaging mode of filling the substrate with entities, the application can support the cavity structure by using a glass material substrate with high Young's modulus, and can make the metal structure in the cavity form a reference layer by arranging the signal line in the cavity, so as to improve the integrity of the signal layer covered by the reference layer, and further reduce the interference of the outside.

Description

Technical Field

[0001] This application belongs to the field of circuit structure technology, and in particular relates to a high-speed signal transmission structure, circuit and electronic device based on stacked cavities. Background Technology

[0002] In existing technologies, solutions for high-speed signal transmission requirements mainly fall into two categories: Firstly, materials need to be upgraded by selecting high-frequency boards with low dielectric constant and low dielectric loss, such as PTFE and hydrocarbon resins, to reduce signal attenuation and delay. However, the dielectric loss of existing materials has already reached its limit. For example, the DF value of existing M9 materials has been firmly fixed at 0.0007~0.0009, and it is difficult to achieve a breakthrough in this loss factor in the short term.

[0003] Secondly, design optimization involves using a multi-engine adaptive algorithm to dynamically adjust impedance, shortening the path length of high-speed signal lines through structural layout optimization, and using blind vias to shorten via length, controlling the differential pair length difference within ±3mil to avoid ground plane interruption. However, such a solution has high algorithm requirements, requires significant R&D investment, and the debugging process relies on high-precision simulation models. Actual operation is limited by the R&D and equipment process capabilities of the packaging plant, resulting in significant deviations and making it difficult to achieve the ideal. Summary of the Invention

[0004] The problem this application aims to solve is to address the high loss in existing high-speed signal transmission by providing an independent technical approach from a structural design perspective. This approach involves using materials with high rigidity to fabricate the cavity, thereby improving the signal's anti-interference capability and reducing the loss value.

[0005] To solve the above-mentioned technical problems, the technical solution adopted in this application is as follows: a high-speed signal transmission structure based on stacked cavities, comprising: a substrate having several layers stacked thereon, and each substrate layer having a metal layer, a through metal structure and a cavity; and a signal path disposed within the cavity for connecting circuit units to transmit high-speed signals.

[0006] In any of the above-described high-speed signal transmission structures based on stacked cavities, each of the substrate layers has: a metal layer on at least one side plane of the substrate; the cavity is disposed on the side of the metal layer or the opposite side of the metal layer; the substrate layers are separated by the metal layers; in each substrate layer, the through metal structure passes through its respective substrate and maintains an electrical connection between the metal layers of adjacent substrates.

[0007] In any of the high-speed signal transmission structures based on stacked cavities described above, the metal layer in each substrate layer covers at least one side of the cavity.

[0008] In any of the above-described high-speed signal transmission structures based on stacked cavities, the through-metal structure includes: a hole penetrating the substrate, and a metal material is disposed in the hole, wherein the metal material is electrically connected to the metal layer.

[0009] In any of the above-described high-speed signal transmission structures based on stacked cavities, the through-metal structure is arranged along the signal path on the outside of the cavity at a preset interval; the preset interval is set to 1 / 10 to 1 / 20 of the wavelength of the electrical signal transmitted in the circuit unit.

[0010] The high-speed signal transmission structure based on stacked cavities as described above, wherein the cavity is hollow, vacuum, or filled with an electrically insulating medium; the loss factor of the electrically insulating medium does not exceed 0.0009.

[0011] In any of the above-described high-speed signal transmission structures based on stacked cavities, the substrate is made of organic or inorganic material; the Young's modulus of the inorganic material is not less than 65 GPa.

[0012] In any of the above-described high-speed signal transmission structures based on stacked cavities, the substrate is made of glass, such as borosilicate glass or quartz glass.

[0013] In addition, this application also provides a circuit in which at least some circuit units are connected by a high-speed signal transmission structure based on stacked cavities as described above.

[0014] In addition, this application also provides an electronic device that includes the circuit described above. Beneficial effects

[0015] This application provides a high-speed signal transmission structure, circuit, and electronic device based on stacked cavities. On a multi-layered stacked substrate, each layer has a metal layer, a through-metal structure, and a cavity. The signal path is arranged within the cavity, providing a structural design scheme to reduce insertion loss and return loss during high-speed signal transmission. This application uses metal layers and through-metal structures to form a single-sided cavity, which, combined with the hollow cavity, significantly reduces signal transmission loss. Compared to existing packaging methods that fill the substrate with solid material, this application uses a glass substrate with high Young's modulus to support the cavity structure. By arranging signal lines within the cavity, the metal structure within the cavity forms a reference layer. This reference layer stack covers the signal layer, improving the integrity of the signal layer's coverage and further reducing external interference. Attached Figure Description

[0016] The embodiments of this application will be described in further detail below with reference to the accompanying drawings: Figure 1This is a schematic diagram of the first implementation of the high-speed signal transmission structure based on stacked cavities in this application; Figure 2 This is a schematic diagram of the second implementation of the high-speed signal transmission structure based on stacked cavities in this application; Figure 3 A schematic diagram of a simulation model for a differential signal with a 100Ω impedance; Figure 4 This is a schematic diagram of the third implementation of the high-speed signal transmission structure based on stacked cavities in this application; Figure 5 for Figure 3 The simulation model shown is a TDR simulation result when an organic material substrate is used; Figure 6 for Figure 3 The simulation model shown contains IL simulation results when an organic substrate is used. Figure 7 for Figure 3 The simulation model shown is a TDR simulation result when one side uses an organic substrate and the other side uses a glass substrate. Figure 8 for Figure 3 The simulation results of IL when one side uses an organic substrate and the other side uses a glass substrate are shown in the simulation model. Figure 9 for Figure 3 The simulation model shown is a TDR simulation result when a glass substrate is used. Figure 10 for Figure 3 The simulation model shown presents the IL simulation results when a glass substrate is used. Figure 11 A cross-sectional view of the electrical connection path formed by the high-speed signal transmission structure based on stacked cavities provided in this application; Figure 12 This is a schematic diagram of the third implementation of the high-speed signal transmission structure based on stacked cavities in this application.

[0017] In the diagram, 1 represents the substrate; 2 represents the metal layer; 3 represents the through-metal structure; 4 represents the signal path; and 5 represents the cavity. Detailed Implementation

[0018] To make the objectives and technical solutions of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0019] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0020] The term "connection" as used in this application can mean a direct connection between components or an indirect connection between components through other components.

[0021] The meaning of "and / or" as used in this application includes both situations where each exists alone or both exist simultaneously.

[0022] In this application, "inner" and "outer" refer to the direction from the inner wall of the cavity to the signal path as "inner" and vice versa, and are not specific limitations on the device mechanism of this application.

[0023] This application provides a high-speed signal transmission structure based on a 3D stacked cavity structure made of multi-layered materials, which can reduce the insertion loss and return loss of high-speed signals with transmission rates of 200Gbps and above during transmission on circuit boards or packaging substrates. Its main structure includes... Figures 1 to 4 Shown: The substrate 1 has several layers stacked on it, and each layer of the substrate is provided with a metal layer 2, a through metal structure 3 and a cavity 5. Signal path 4, located within cavity 5, is used to connect to circuit units such as chip bump or BGA on the back of the package, to transmit signals. Figure 11The method shown achieves direct signal paths between chips by connecting conductive structures layer by layer to the same signal path within the stacked structure, or between chips and BGAs by connecting conductive structures layer by layer to the BGA balls at the bottom of the stacked structure. This enables high-speed interconnection between chips and between chips and the BGA on the back of the package, facilitating the transmission of high-speed signals. Electrical signals can be transmitted layer by layer between different chip bumps and between chips and the BGA on the back of the package using the through-metal structures of each substrate layer. Furthermore, because such a transmission structure can form a signal shielding cavity around its perimeter using metal layers and other through-metal structures, signal attenuation and transmission loss during transmission can be effectively reduced.

[0024] Therefore, after the substrates are stacked and fixed, the signal path in each substrate can be shielded by the metal layers attached to its adjacent substrates and the through-hole metal structure outside the cavity. Thus, external interference within almost 360 degrees of the high-speed signal transmission path can be shielded by the aforementioned metal shielding. Compared to traditional packaging methods that fill the substrate with solid signal transmission lines, this application can use a material with high Young's modulus as the substrate. By using low-loss-factor materials such as glass, the cavity structure can be supported by these material structures. Furthermore, the hollow or vacuum space within the cavity, or the electrically insulating medium filled in it, can provide an even lower loss factor, thereby further reducing the loss of the high-speed signal transmission structure of this application.

[0025] In the first implementation provided in this application, the high-speed signal transmission structure based on stacked cavities can be referred to as follows: Figure 1 As shown, a metal layer 2 is provided on one side plane of the substrate, and grooves are alternately formed on the opposite side of the metal layer 2 and on the metal layer to form cavities for arranging signal paths 4. Each substrate can further have an embedded metal wall in the groove of its cavity 5. By arranging metal on the side wall of the cavity, a complete shielding layer can be provided for one side of the high-speed signal line, effectively reducing external interference. The next substrate adjacent to the groove structure can have its metal layer corresponding to the groove position removed. Thus, each signal path can be arranged on the top surface of the next substrate after the metal layer along the signal path has been removed. The metal layer arranged on the bottom surface of the next substrate, the metal layer arranged on the top surface of the next substrate corresponding to the outer area of ​​the cavity 5, the metal surface arranged on the inner wall of the groove in the cavity of the upper substrate, and the through metal structure in the substrate that runs longitudinally through the signal path form a reference layer surrounding the signal path. By stacking the reference layer to cover the signal layer, the integrity of the signal layer coverage is improved, further reducing external interference.

[0026] In the first embodiment provided in this application, two adjacent cavities 5 on the same substrate layer, spaced apart on both sides of the same through-metal structure, can respectively have their groove structures formed on the top surface of the lower substrate layer and the bottom surface of the upper substrate layer. Regardless of which side of the substrate the groove is formed on, in this embodiment, a metal layer and a metal reference layer structure connected to the upper and lower substrate layers can be arranged at the horizontal bottom and sidewalls of the groove structure. The signal path in the cavity 5 can be arranged on the opposite side of the metal layer in the groove structure using a single wiring, a double wiring, or multiple parallel wiring. Thus, one side of the signal path is attached to the substrate surface, and the other side is enclosed in the metal layer inside the cavity. For the signal path on the side attached to the substrate surface, its influence on the surrounding paths can be shielded by the metal layer opposite to that side of the substrate. In this embodiment, the concave cavity of the substrate is filled with shielded signals, and the sidewall of the cavity is provided with a copper-plated metal layer to serve as a ground plane for drilling. Figure 1 In the signal line arrangement shown, since the cavity is opposite the signal side, the cavity is filled with a signal reference layer. When the dielectric layers are stacked and pressed together, the reference layer inside the cavity acts like a lid, covering the signal layer. This allows the coverage on the signal side to be completely connected to the through-holes in the upper and lower metal structures that connect the upper and lower layers. Based on a similar principle, this application can also refer to... Figure 12 As shown, while providing a ground plane for the cavity sidewalls with a copper-clad metal layer, the signal path is arranged on the opposite side of the metal layer in the cavity, and the bottom of the cavity is uniformly arranged on the upper surface of each substrate. This structure can still provide a shielding structure for each signal path after the substrates are stacked and pressed layer by layer, reducing signal loss.

[0027] In this application Figure 2 In the second implementation provided, the high-speed signal transmission structure based on stacked cavities can have a metal layer 2 on one side of the substrate, and then a groove is formed on the opposite side of the metal layer 2 in the substrate to form a cavity for arranging the signal path 4. Each substrate can further have an embedded metal wall in the groove of its cavity 5, but a certain signal isolation distance needs to be reserved between the metal wall and the metal structure of the signal path in the area where the signal path 4 is arranged at the bottom of the groove. The upper substrate adjacent to the groove structure can be uniformly covered with a complete metal layer on the surface of its mating groove opening. Thus, each group of signal paths can be arranged in the bottom of the cavity after removing the metal bottom wall along the signal line. Through the bottom surface of the substrate layer where the groove is located, the metal layer arranged on the bottom surface of the substrate above the groove opening, the metal surface arranged on the inner wall of the groove in the cavity of this substrate layer, and the through metal structure in the substrate that runs longitudinally through the signal path, a reference layer is formed around the signal path. By using the stacked reference layer to cover the signal layer, a comprehensive shielding layer coverage is achieved on one side of the high-speed signal line, improving the integrity of the signal layer coverage and effectively reducing external interference to the high-speed signal line.

[0028] In the second embodiment provided in this application, two adjacent cavities 5 on the same substrate layer, spaced apart on both sides of the same through-metal structure, can have their groove structures formed on the top surface of the same substrate layer. Regardless of which side of the substrate the groove is formed on, in this embodiment, a metal reference layer structure connected to the bottom metal layer of the upper substrate and surrounding the signal path can be arranged at the horizontal bottom and sidewalls of the groove structure. The signal path in the cavity 5 can be arranged in the groove structure using a single wiring, dual wiring, or multiple parallel wiring. The location of the arrangement requires that the metal layer at the bottom of the groove be formed with an isolation groove along the direction of the signal line, so that the structure of the signal path is directly arranged on the substrate surface inside the groove to avoid the signal being incorrectly transmitted to the metal reference isolation structure around the groove. Thus, one side of the signal path is attached to the substrate surface, and the other side is enclosed in the metal layer inside the cavity. The influence of the signal path on the surrounding signal lines is shielded by the metal layer opposite the substrate on this side and the metal layer above the groove. In this embodiment, the concave cavity of the substrate is filled with shielded signals, and the sidewall of the cavity is provided with a copper-plated metal layer for drilling and grounding. Figure 2 In the signal line arrangement shown, the metal layer in the cavity is directly placed on the side of the signal path, and the metal layer on the bottom of the adjacent substrate covers the cavity with a signal reference layer. After the dielectric layers are stacked and pressed together, the reference layer in the cavity can cover the signal layer in a lid-like manner, thus making the coverage of the signal layer more complete. The through-holes connecting the upper and lower layers are connected by the through-metal structure.

[0029] The third embodiment of this application can be based on the previous embodiments, referring to... Figure 4 The method shown removes the internal metal structure of the substrate cavity, and only the metal layer 2 arranged at the bottom of this layer and the adjacent layer of the substrate provides interference protection for the communication lines within the cavity 5. Appropriate spacing is selected between each layer according to the frequency of the signal in each signal path, and a through-metal structure 3 is arranged along the line of that signal path in the substrate, such as... Figure 4 As shown, the structure is separated by metal layers 2 between each substrate layer; in each substrate layer, the through-metal structure 3 penetrates through its respective substrate and maintains electrical connection between the metal layers 2 of adjacent substrates. This simplifies the internal cavity structure design and reduces signal loss.

[0030] Regardless of the specific arrangement, this application can construct a cavity structure with straight or curved lines on the glass plane according to the signal direction, as in the designs of the aforementioned embodiments 1, 2, and 3. The signal line can be routed to the bottom of the cavity or the surface of the structure opposite the cavity. It only requires that in each substrate layer, the metal layer 2 at least covers one side of the cavity 3. This, combined with the through-metal structure 3 composed of the perforations through the substrate and the metal material filling them, utilizes the electrical connection between the metal material and the metal layer 2 to achieve signal enclosure and protection in the signal path.

[0031] In application, the through metal structure 3 is generally arranged on the outside of the cavity 3 along the signal path 4 at a preset interval; the specific interval of the through metal structure 3 in each signal path can be determined according to 1 / 10 to 1 / 20 of the wavelength of the electrical signal transmitted in the line or adjacent line.

[0032] To reduce signal loss due to the signal transmission structure of this application, in a preferred embodiment, corresponding electrical isolation media can be arranged in the cavities 3 of each substrate layer. This allows for better transmission parameters by limiting the loss factor of the media to no more than 0.0009. For example, in some implementations, the cavity can be set to a vacuum or directly filled with air. Regardless of the method, a loss factor (DF) of less than 0.0001 can provide isolation of electrical signals around the signal lines. In other embodiments, materials such as Taikoo EM-896K3 (M9 series) can be selected, with a DF value of 0.0008 at an ultra-high frequency of 100GHz. As long as the DF parameters of these high-frequency materials can be maintained between 0.0007 and 0.0009, effective loss suppression can be provided.

[0033] To support the stacked materials and prevent material deformation from affecting the impedance of signal lines and causing severe signal attenuation due to impedance discontinuity, this application uses inorganic materials for each substrate 1. Specifically, it selects borosilicate glass or quartz glass with a Young's modulus of not less than 65 GPa. These materials not only possess high Young's modulus characteristics that effectively support the cavity structure but also have low DF (dielectric displacement) values. Quartz glass can achieve a DF below 0.0005, effectively reducing signal attenuation. Alternatively, other materials with high Young's modulus, such as ceramics, can be used in conjunction with glass or alone in this embodiment; however, their DF is not as low as glass, which may increase signal line losses.

[0034] In the above structure, the longitudinal yellow line connecting the two adjacent substrates only needs to connect the metal layer signal on the upper and lower sides of its structure to achieve protection of the electrical signal inside the substrate, without the need to use the traditional method to ensure accurate grounding and form a grounding hole for high-speed signals in conventional design.

[0035] In different schemes, the high-speed signal layout line can be placed on the dielectric layer opposite the cavity, and the corresponding signal can be placed inside the cavity (i.e., similar to...). Figure 1 , Figure 2 Using the metal surface at the bottom of the recessed cavity as a reference plane, and grounding this reference plane, along with drilling holes around the internal signal transmission lines to short-circuit the corresponding reference layers, can effectively isolate and protect high-speed signals within the enclosed area. In other ways, this application can also place the high-speed signal at the bottom of the cavity, place the corresponding signal as a reference plane on the opposite side of the cavity, and use drilling around the signal line to short-circuit the corresponding reference layer, which can also isolate and protect the high-speed signal.

[0036] Regardless of the structure used, the cavity formed by the 3D multilayer substrate stacking proposed in this application can significantly reduce signal transmission loss by placing high-speed signal lines in cavities with low DF values, such as air or vacuum, with one side of the high-speed signal line referencing air as the primary medium. Furthermore, the other side of the high-speed signal line is not limited to any specific organic or inorganic material used in its stacking; the cavity structure of this application can effectively reduce the losses caused by traditional substrate materials.

[0037] Reference Figure 3 The provided simulation models were used to simulate and test the transmission loss parameters of different substrate materials:

[0038] Depend on Figures 5 to 10 As shown in the simulation structures, based on a signal length of 5mm, at a high frequency of 120GHz, the stacked signal transmission structure with a hollow cavity constructed using an organic material substrate can improve the insertion loss of the organic material itself on both sides of the dielectric layer in Simulation 1, achieving an overall insertion loss of 3dB. For the stacked signal transmission structure with a hollow cavity used in Simulation 2, which has one side made of organic material and the other side made of glass material, the overall insertion loss can be further optimized to 2.5dB. When the scheme provided in Simulation 3, which has one side made of a hollow structure and the other side made of glass material, is adopted, the insertion loss of the stacked signal transmission structure with a hollow cavity provided in this application can be further reduced to 1.7dB, demonstrating a significant advantage in insertion loss.

[0039] In summary, by replacing the dielectric layer on one side of the signal transmission line with air or vacuum, this application can reduce the DF value on that side to near 0. This allows the use of a vertically stacked 3D cavity structure and a metal reference layer structure arranged therein to avoid signal interference between existing stacked structures, reduce the overall insertion loss of the transmission structure, obtain better signal transmission performance, and reduce interference with internal communication content during signal transmission.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A high-speed signal transmission structure based on stacked cavities, characterized in that, include: The substrate (1) has several layers stacked on it, and each substrate layer is provided with a metal layer (2), a through metal structure (3) and a cavity (5). The signal path (4) is located inside the cavity (5) and is used to connect the circuit unit to transmit high-speed signals.

2. The high-speed signal transmission structure based on stacked cavities as described in claim 1, characterized in that, Each of the aforementioned substrate layers is respectively: A metal layer is provided on at least one side plane of the substrate (2); The cavity (5) is provided on the side of the metal layer (2) or on the opposite side of the metal layer (2); The substrate layers are separated by the metal layer (2); In each substrate layer, the through metal structure (3) penetrates through the substrate in which it is located and maintains an electrical connection between the metal layers (2) of two adjacent substrates.

3. The high-speed signal transmission structure based on stacked cavities as described in claim 2, characterized in that, In each substrate layer, the metal layer (2) covers at least one side of the cavity (5).

4. The high-speed signal transmission structure based on stacked cavities as described in claim 2, characterized in that, The through-metal structure (3) includes: a through-hole in the substrate, and a metal material is provided in the through-hole, and the metal material is electrically connected to the metal layer (2).

5. The high-speed signal transmission structure based on stacked cavities as described in claim 4, characterized in that, The through-metal structure (3) is arranged on the outside of the cavity (5) along the signal path (4) at a preset interval; The preset interval distance is set to 1 / 10 to 1 / 20 of the wavelength of the electrical signal transmitted in the circuit unit.

6. The high-speed signal transmission structure based on stacked cavities as described in claims 1-5, characterized in that, The cavity (5) is set to be hollow or vacuum or filled with an electrical isolation medium; the loss factor of the electrical isolation medium does not exceed 0.0009.

7. The high-speed signal transmission structure based on stacked cavities as described in claims 1-5, characterized in that, The substrate (1) is made of inorganic material, and the Young's modulus of the inorganic material is not less than 65 GPa.

8. The high-speed signal transmission structure based on stacked cavities as described in claim 7, characterized in that, The substrate (1) is made of glass.

9. A circuit, characterized in that, At least some of the circuit units in the circuit are connected by the high-speed signal transmission structure based on stacked cavities as described in claims 1-8.

10. An electronic device, characterized in that, It includes the circuit described in claim 9.

Images