3D integrated shielding transmission structure

Abstract

The utility model provides a 3D integrated shielding transmission structure, which comprises a microwave dielectric substrate, a radio frequency signal transmission inner conductor connected between the microwave dielectric substrate and a functional module, a quasi-coaxial shielding layer and a solder ball shielding separation cavity, the metal shielding layers respectively cover the upper surface and the lower surface of the microwave dielectric substrate; and the metal through hole and the strip line are connected in the microwave dielectric substrate. According to the utility model, radio frequency output signals are led out by adopting a quasi-coaxial structure, the periphery of each output radio frequency signal is provided with three layers of grounding solder balls, and the vertical transmission structure can effectively ensure isolation of the radio frequency signals; a strip line is integrated in a substrate integrated waveguide, upper and lower metal layers and left and right rows of through holes are reserved, and an inner conductor is added in a medium inner layer, so that a double-conductor structure is formed, and a TEM mode can be propagated; and during multi-signal transmission, layered wiring is carried out in the multi-layer substrate, and a 3D substrate integrated shielding transmission structure is adopted, so that design realization of a miniaturized complex microwave assembly is facilitated.

Description

Technical Field

[0001] The utility model relates to the technical field of electrical components, and particularly relates to a 3D integrated shielding transmission structure. Background Art

[0002] The miniaturization of the system and the increase in integration level have significantly reduced the circuit feature size, sharply reduced the spacing between transmission lines, increased the electromagnetic field energy density, inevitably exacerbated the crosstalk between signals, and made the impact on the overall performance of the circuit more obvious. In the microwave and millimeter-wave frequency bands, the signal radiation is enhanced, the combined frequencies of the mixer circuit are complex, and the problem is more serious.

[0003] The traditional transmission structure outputs radio frequency signals in the form of leads or QFNs for components, and the integrated interconnections such as microstrip lines and striplines. The radio frequency signal transmission path is an open structure, facing serious crosstalk; the discrete waveguide interconnections such as rectangular waveguides and circular waveguides are limited by large volume and difficult integration; the new optical interconnections have limitations such as high cost and poor compatibility. As a new type of planar interconnection structure, the substrate integrated waveguide (SIW) realizes the functions of traditional waveguides by replacing the waveguide metal sidewalls with a metallized via array on a dielectric substrate with metal layers on the upper and lower surfaces, and has gradually been applied in the micro-system interconnection technology. However, due to the cut-off frequency characteristic of SIW, the passive circuits based on SIW occupy a large circuit area in the microwave frequency band, thus restricting its application in compact circuits. How to better integrate the high shielding performance characteristics of the substrate integrated waveguide with other microwave planar transmission lines to solve the problems of miniaturization and high-performance engineering applications is the key technology that needs to be focused on and broken through in the field of radio frequency microsystems.

[0004] Therefore, a structure that can achieve shielding transmission and effectively suppress the stray signal level caused by crosstalk is needed. Summary of the Invention

[0005] The utility model is to solve the problems of shielding output of radio frequency signals and how to suppress crosstalk, and provides a 3D integrated shielding transmission structure. It includes a microwave dielectric substrate, a radio frequency signal transmission inner conductor, a coaxial-like shielding layer, a solder ball shielding cavity connected between the microwave dielectric substrate and the functional module, a metal shielding layer respectively covering the upper and lower surfaces of the microwave dielectric substrate, and metal vias and striplines connected in the microwave dielectric substrate. The radio frequency output signal of the utility model is led out by a coaxial-like structure, and there are three layers of grounded solder balls around each output radio frequency signal. This vertical transmission structure can effectively ensure the isolation of radio frequency signals; the stripline is integrated inside the substrate integrated waveguide, retaining the upper and lower metal layers and two rows of vias on the left and right, and adding an inner conductor in the dielectric inner layer, thus forming a two-conductor structure that can propagate TEM modes; when multiple signals are transmitted, hierarchical wiring is carried out in multiple substrate layers, and a 3D substrate integrated shielding transmission structure is adopted, which is more conducive to the design and implementation of miniaturized complex microwave components.

[0006] The utility model provides a 3D integrated shielding transmission structure, which includes a microwave dielectric substrate, a radio frequency signal transmission inner conductor, a coaxial-like shielding layer, a solder ball shielding cavity connected between the microwave dielectric substrate and the functional module, a metal shielding layer covering the upper and lower surfaces of the microwave dielectric substrate respectively, and metal vias and strip lines connected in the microwave dielectric substrate;

[0007] The radio frequency signal transmission inner conductor is a solder ball. Both the coaxial-like shielding layer and the solder ball shielding cavity are BGA ball grid arrays composed of solder balls. The coaxial-like shielding layer surrounds the radio frequency signal transmission inner conductor to form a coaxial-like structure, and the coaxial-like structure leads out the radio frequency signal inside the functional module. The solder ball shielding cavity surrounds the outside of the coaxial-like shielding layer;

[0008] The lower part of the coaxial-like structure is connected to the strip line. Metal vias are evenly distributed on both sides of the strip line, and the metal vias and the metal shielding layer form a closed structure;

[0009] Both ends of the strip line are respectively connected to the coaxial-like structures of different functional modules for signal transmission.

[0010] In a preferred embodiment of the 3D integrated shielding transmission structure of the utility model, the solder ball shielding cavity is a three-layer grounded BGA ball implantation surrounding the outside of the coaxial-like shielding layer.

[0011] In a preferred embodiment of the 3D integrated shielding transmission structure of the utility model, the solder balls of the radio frequency signal transmission inner conductor, the coaxial-like shielding layer and the solder ball shielding cavity all have a diameter of 450 μm, and the diameter of the coaxial-like structure is 800 μm.

[0012] In a preferred embodiment of the 3D integrated shielding transmission structure of the utility model, the microwave dielectric substrate, the metal shielding layer, the metal vias and the strip line form a 3D substrate integrated transmission structure;

[0013] The radio frequency signal transmission inner conductor is connected to the strip line through the metal vias.

[0014] In a preferred embodiment of the 3D integrated shielding transmission structure of the utility model, the main working mode of the 3D substrate integrated transmission structure is the TE10 mode, and the TEM mode is propagated through the radio frequency signal transmission inner conductor.

[0015] In a preferred embodiment of the 3D integrated shielding transmission structure of the utility model, the number of the 3D substrate integrated transmission structures can be two or more and are located on different layers, and the number of functional modules is twice the number of the 3D substrate integrated transmission structures.

[0016] In a preferred embodiment of the 3D integrated shielding transmission structure of the utility model, the material of the microwave dielectric substrate is TSM-DS3.

[0017] For a 3D integrated shielding transmission structure according to the present utility model, as a preferred embodiment, the width of the strip line is 0.36 mm.

[0018] For a 3D integrated shielding transmission structure according to the present utility model, as a preferred embodiment, the distance from the center line of the strip line to the metal vias on both sides is 0.82 mm.

[0019] For a 3D integrated shielding transmission structure according to the present utility model, as a preferred embodiment, the functional module can be a mixing module or a local oscillator module.

[0020] The technical problem solved by the present utility model is that in the design of miniaturized millimeter-wave products, system-level advanced high-density packaging technologies are widely used. Among them, the metal package has excellent shielding characteristics. However, the traditional external output form is an open structure, which cannot achieve the shielding output of radio frequency signals. Therefore, a high-performance vertically fully enclosed shielding transmission structure needs to be designed to truly achieve the shielding transmission with the outside.

[0021] The miniaturization of the system exacerbates the signal interference between high-frequency transmission lines. Traditional integrated interconnections such as microstrip lines and strip lines are open structures and face serious crosstalk. Especially in the design of ultra-wideband mixing circuits, the power of the local oscillator signal is relatively high, and a large number of combined frequencies and intermodulation signals (spurious signals) will be generated in the highly integrated inter-board transmission lines. Therefore, a new type of high-isolation radio frequency transmission structure is selected to effectively suppress the spurious signal level caused by crosstalk.

[0022] The technical solution of the present utility model is as follows:

[0023] The external output interface form of the advanced high-density packaging case adopts a ball grid array (BGA), and the radio frequency output signal is led out in a coaxial-like structure. There are three layers of ground solder balls around each output radio frequency signal. This vertical transmission structure can effectively ensure the isolation of radio frequency signals.

[0024] The advanced high-density packaging cases are interconnected by multiple layers of substrates. The transmission of radio frequency signals is designed and simulated in the form of substrate integrated waveguide (SIW) combined with strip line. The substrate integrated waveguide (SIW) is a waveguide integrated on a substrate, which is composed of a dielectric substrate, its upper and lower metal shielding layers, and two rows of metal vias on the left and right. The main working mode is the TE10 mode. The strip line is integrated inside the substrate integrated waveguide, retaining the upper and lower metal layers and two rows of vias on the left and right, and adding an inner conductor in the dielectric inner layer, thus forming a two-conductor structure that can propagate the TEM mode.

[0025] Identify strong interference radio frequency signals. When multiple signals are transmitted, hierarchical wiring is carried out in the multi-layer substrate, and a 3D substrate integrated shielding transmission structure is adopted, which is more conducive to the design and implementation of miniaturized complex microwave components.

[0026] The utility model has the following advantages:

[0027] (1) The BGA ball grid array technology replaces the lead frame with a tin ball array. Its input and output ports are distributed in the form of a cylinder or columnar solder joints in an array, which is particularly suitable for vertical transmission structures. It has the characteristics of a large number of pins, good electrical and physical properties, and low production cost. Especially for the electromagnetic compatibility performance in the radio frequency field, it is extremely excellent.

[0028] (2) It combines the advantages of easy integration of traditional planar integrated interconnections and the wide frequency band, low loss, and low crosstalk of waveguides, and is more suitable for the radio frequency signal transmission design of high-performance complex electronic systems.

[0029] (3) The traditional transmission line with a tiled design realizes isolation by increasing the spacing and ground vias, and it is inevitable that it cannot meet the miniaturization requirements. When transmitting multiple signals, a 3D transmission structure hierarchical design is adopted, and shielding is achieved by using a large-area metal layer in the middle. It is more conducive to the realization of miniaturization on the premise of ensuring a high isolation effect. Description of the Drawings

[0030] Figure 1 It is a schematic diagram of a coaxial-like structure of a 3D integrated shielding transmission structure;

[0031] Figure 2 It is a schematic diagram of the structure of a 3D integrated shielding transmission structure;

[0032] Figure 3 It is a simulation model diagram of a 3D substrate integrated transmission structure of a 3D integrated shielding transmission structure;

[0033] Figure 4 It is a schematic diagram of the insertion loss simulation result of a 3D integrated shielding transmission structure;

[0034] Figure 5 It is a schematic diagram of the signal isolation degree result of a 3D integrated shielding transmission structure.

[0035] Reference Signs:

[0036] 1. Microwave dielectric substrate; 2. Inner conductor for radio frequency signal transmission; 3. Coaxial-like shielding layer; 4. Tin ball shielding cavity; 5. Metal shielding layer; 6. Metal via; 7. Strip transmission line. Detailed Embodiments

[0037] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments.

[0038] Embodiment 1

[0039] As Figures 1 to 3As shown in the figure, a 3D integrated shielding transmission structure is composed of an external interface of a functional module and a 3D substrate integrated transmission structure. The external interface of the functional module includes an inner conductor 2 for RF signal transmission, a coaxial-like shielding layer 3, and a solder ball shielding cavity 4. The 3D substrate integrated transmission structure includes a microwave dielectric substrate 1, a metal shielding layer 5, metal vias 6, and a strip transmission line 7.

[0040] Figure 1 It is a schematic diagram of the BGA vertical transmission structure for the RF signal of the functional module. The RF signal inside the functional module is led out through a coaxial-like transmission structure composed of solder balls. The coaxial-like transmission structure includes an inner conductor 2 for RF signal transmission and a coaxial-like shielding layer 3, and is surrounded by a solder ball shielding cavity 4 formed by a solder ball array around it. The BGA solder balls use high-lead material solder balls, the diameter d1 of the solder balls is 450μm, and the diameter l1 of the coaxial-like structure is 800μm.

[0041] Figure 2 It is a schematic diagram of the 3D substrate integrated transmission structure, which is composed of a microwave dielectric substrate 1, a metal shielding layer 5, metal vias 6, and a strip line 8. The material of the microwave dielectric substrate 1 is TSM-DS3, which is a ceramic-filled reinforced material with a very low glass fiber content, a dielectric constant of 3, and a loss factor of 0.0014@10GHz. The upper and lower surfaces are covered by a metal shielding layer 5, and in the middle is a strip line 8 with a width of 0.36mm. Metal vias 6 are evenly distributed on both sides of the strip line 8, forming a closed structure with the metal shielding layer 5. The distance from the metal vias on both sides to the center line of the strip line is 0.82mm. Two strong interference signals are transmitted in layers. Figures 4 to 5 It is a simulation model diagram. Figure 5 It is the S-parameter result after simulation. It can be seen that the insertion loss of both transmission structures can be less than 0.13dB. The isolation between the two signals is greater than 130dB below 40GHz and greater than 145dB below 20GHz, with outstanding superiority, which is nearly 80dB higher than the traditional open planar transmission structure.

[0042] The 3D integrated shielding transmission structure of the present invention realizes the goal of high-performance design of a miniaturized, ultra-wideband, and multi-band composite RF microsystem through reasonable design of the mixing architecture, BGA shielding vertical transmission design of the RF signal of the functional module, and 3D substrate integrated transmission structure design of the multi-layer substrate, and can be applied as a general way to meet the requirements of RF microsystem circuit design.

[0043] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and the inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A 3D integrated shielding transmission structure, characterized in that: It includes a microwave dielectric substrate (1), a radio frequency signal transmission inner conductor (2), a coaxial-like shielding layer (3), a solder ball shielding cavity (4) connected between the microwave dielectric substrate (1) and functional modules, metal shielding layers (5) respectively covering the upper and lower surfaces of the microwave dielectric substrate (1), and metal vias (6) and striplines (7) connected in the microwave dielectric substrate (1); The radio frequency signal transmission inner conductor (2) is a solder ball. The coaxial-like shielding layer (3) and the solder ball shielding cavity (4) are both BGA ball grid arrays composed of solder balls. The coaxial-like shielding layer (3) surrounds the radio frequency signal transmission inner conductor (2) to form a coaxial-like structure, and the coaxial-like structure leads out the radio frequency signal inside the functional module. The solder ball shielding cavity (4) surrounds the outside of the coaxial-like shielding layer (3); The lower part of the coaxial-like structure is connected to the stripline (7). The metal vias (6) are evenly distributed on both sides of the stripline (7), and the metal vias (6) and the metal shielding layer (5) form a closed structure; Both ends of the stripline (7) are respectively connected to the coaxial-like structures of different functional modules for signal transmission.

2. The 3D integrated shielding transmission structure according to claim 1, characterized in that: The solder ball shielding cavity (4) is a three-layer grounded BGA ball implantation surrounding the outside of the coaxial-like shielding layer (3).

3. A 3D integrated shielding transmission structure according to claim 1, characterized in that: The solder balls of the radio frequency signal transmission inner conductor (2), the coaxial-like shielding layer (3) and the solder ball shielding cavity (4) all have a diameter of 450 μm, and the diameter of the coaxial-like structure is 800 μm.

4. A 3D integrated shielding transmission structure according to claim 1, characterized in that: The microwave dielectric substrate (1), the metal shielding layer (5), the metal vias (6) and the stripline (7) form a 3D substrate integrated transmission structure; The radio frequency signal transmission inner conductor (2) is connected to the stripline (7) through the metal via (6).

5. A 3D integrated shielding transmission structure according to claim 4, characterized in that: The working dominant mode of the 3D substrate integrated transmission structure is the TE10 mode, and the TEM mode propagates through the radio frequency signal transmission inner conductor (2).

6. A 3D integrated shielding transmission structure according to claim 4, characterized in that: The number of the 3D substrate integrated transmission structures can be two or more and they are located on different layers. The number of functional modules is twice the number of the 3D substrate integrated transmission structures.

7. A 3D integrated shielding transmission structure according to claim 1, characterized in that: The material of the microwave dielectric substrate (1) is TSM-DS3.

8. A 3D integrated shielding transmission structure according to claim 1, characterized in that: The width of the stripline (7) is 0.36 mm.

9. A 3D integrated shielding transmission structure according to claim 1, characterized in that: The distance from the metal vias (6) on both sides to the center line of the stripline (7) is 0.82 mm.

10. A 3D integrated shielding transmission structure according to claim 1, characterized in that: The functional module can be a mixing module or a local oscillator module.

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