A composite interconnection layer and an active subarray based on the same

Abstract

The present invention discloses a composite interconnection layer and an active subarray based on the same. The composite interconnection layer includes a micro coaxial network layer and a low-frequency network layer connected thereto; low-frequency connectors and radio-frequency connectors are arranged on the lower surface of the low-frequency network layer. After low-frequency signals and radio-frequency signals are respectively input through the low-frequency connectors and the radio-frequency connectors, they are distributed through the low-frequency network layer and the micro coaxial network layer, and the vertical transfer of heat flow from the micro coaxial network layer to the low-frequency network layer is completed; the micro coaxial network layer includes N levels of a total of several micro coaxial networks, and N is a positive integer. The composite interconnection layer and the active subarray based on the same disclosed by the present invention can realize high-isolation, low-loss multi-port millimeter-wave signal distribution and transmission, as well as the transmission and distribution of control and power supply signals, and have the advantages of high integration, light weight, low profile, small loss, good heat conduction performance, etc.

Description

Technical Field

[0001] The present invention belongs to the field of phased array antennas, and particularly relates to a composite interconnection layer and an active sub-array based on the same. Background Art

[0002] High integration is the future development trend of phased array antennas. With the development of microsystem technology and wafer integration technology, it has become an effective means to improve phased array antennas. In recent years, relevant research results have been continuously reported in developed countries such as the United States, Germany, and France. The main research results focus on the active part of the RF front end, and less research has been done on the interconnection required to form a phased array. There are also some research on the architecture of wafer integrated arrays in China, such as stacked sub-arrays. For phased array antennas in the Ka band and above, especially those using microsystems or wafer integrated arrays, the element spacing is very small, the available area is small, the profile is low, and the integration degree is extremely high, and the interconnection design is greatly restricted.

[0003] The interconnection network used in wafer integrated millimeter wave sub-arrays needs to meet requirements such as being thin and light, having small loss, wide bandwidth, being able to transmit high and low frequency signals at high density, and the coefficient of thermal expansion of the substrate matching that of the wafer RF front end (silicon-based or other wafer materials). The expansion coefficient of traditional microwave boards is quite different from that of silicon. High-temperature ceramics have large losses in the millimeter wave band, while low-temperature ceramics have disadvantages such as moisture absorption and need to be used in a separate airtight manner, which is not flexible. High-density wiring can be achieved on silicon-based wafers, and the material is the same as that of the RF front end, without the risk of thermal mismatch. However, since silicon is a semiconductor, using traditional transmission lines such as strip lines on silicon-based wafers has the problem of excessive loss.

[0004] Currently, there is relevant research on silicon-based micro coaxial transmission lines internationally, but there is no research report on micro coaxial networks, nor is there an integrated application of micro coaxial networks through aluminum nitride substrates, metal carriers, and silicon-based RF front ends. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a composite interconnection layer, which includes a micro coaxial network layer 21 and a low-frequency network layer 20 connected thereto; a low-frequency connector 4 and a radio frequency connector 6 are arranged on the lower surface of the low-frequency network layer 20. After the low-frequency signal and the radio frequency signal are respectively input through the low-frequency connector 4 and the radio frequency connector 6, they are distributed through the low-frequency network layer 20 and the micro coaxial network layer 21, and the vertical transfer of heat flow from the micro coaxial network layer 21 to the low-frequency network layer 20 is completed; the micro coaxial network layer 21 includes N levels of a total of several micro coaxial networks, and N is a positive integer.

[0006] Furthermore, the coefficient of thermal expansion of the material of the low-frequency network layer 20 is greater than that of the material of the micro coaxial network layer 21.

[0007] Further, the micro coaxial network includes a first micro coaxial network 16 and a second micro coaxial network 8. Both the first micro coaxial network 16 and the second micro coaxial network 8 include three through-hole ports. The through-hole ports of the first micro coaxial network 16 include a middle through-hole port on its lower surface, a left through-hole port and a right through-hole port on both sides of the middle through-hole. The through-hole ports of the second micro coaxial network 8 include two through-hole ports on its upper surface and one through-hole port on its lower surface. The N-level micro coaxial network includes the second micro coaxial networks 8 on its upper side and one first micro coaxial network 16 of the first level, two first micro coaxial networks 16 of the second level,..., the first micro coaxial networks 16 of the nth level,..., the second micro coaxial networks 8 of the (N - 1)th level below the second micro coaxial network 8, where n is a positive integer from 1 to N. The first micro coaxial networks 16 from the first to the (N - 1)th level are connected by a binary tree connection method. Specifically, the left through-hole port and the right through-hole port of the first micro coaxial network 16 of the (m - 2)th level are respectively connected to the middle through-hole ports of different first micro coaxial networks 16 of the (m - 1)th level. The middle through-hole of the first micro coaxial network 16 of the first level is connected to the RF connector 6. The left through-hole port and the right through-hole port of the first micro coaxial network 16 of the (N - 1)th level are respectively connected to the through-hole ports on the lower surface of different second micro coaxial networks 8 of the Nth level, where m is a positive integer from 3 to N.

[0008] Further, the material of the micro coaxial network layer 21 is silicon, and the material of the low-frequency network layer 20 is aluminum nitride or aluminum oxide. The micro coaxial network layer 21 and the low-frequency network layer 20 are connected by a large-area welding method.

[0009] Further, the micro coaxial networks are connected by an amplification chip 14.

[0010] Further, the micro coaxial networks are connected by gold wires.

[0011] Further, a cavity 17 is provided on the upper surface of the low-frequency network layer 20. The amplification chip 14 or the gold wire for connecting the micro coaxial networks is placed in the cavity 17. After the micro coaxial network 21 and the low-frequency network layer 20 are welded through a welding surface 15, the cavity 17 becomes an airtight environment.

[0012] Further, both the low-frequency network layer 20 and the micro coaxial network layer 21 are flat cuboids.

[0013] An active sub-array is also proposed. The active sub-array is based on the above-mentioned composite interconnection layer. The active sub-array further includes a wafer radio frequency front-end 2 and a metal carrier 5. The upper surface of the micro coaxial network layer 21 is connected to the wafer radio frequency front-end 2, and the lower surface of the low-frequency network layer 20 is connected to the metal carrier 5. The low-frequency connector 4 and the radio frequency connector 6 are arranged on the lower surface of the low-frequency network layer 20 and pass through the metal carrier 5. The low-frequency signal and the radio frequency signal are respectively input through the low-frequency connector 4 and the radio frequency connector 6, and are distributed by the low-frequency network layer 20 and the micro coaxial network layer 21 and then transmitted to the wafer radio frequency front-end 2. Thus, the composite interconnection layer 3 completes the vertical transfer of heat flow from the wafer radio frequency front-end 2 to the metal carrier 5.

[0014] Further, in the direction from the wafer radio frequency front-end 2 to the metal carrier 5, the coefficients of thermal expansion of the materials of the wafer radio frequency front-end 2, the micro coaxial network layer 21, the low-frequency network layer 20, and the metal carrier 5 increase one by one.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1) The composite interconnection layer adopts an overlapping integrated design of a silicon layer and an aluminum nitride layer. The upper layer is a planar silicon-based micro coaxial network, and the lower layer is a planar aluminum nitride low-frequency network. The active chip is placed in the aluminum nitride cavity and is interconnected with the micro coaxial network by using gold wires or flip-chip bonding. The entire interconnection layer is designed in a flattened manner. Through this integration method, the integration degree is greatly improved, and the profile height and weight of the interconnection layer are reduced.

[0017] 2) The radio frequency signal adopts a silicon-based micro coaxial interconnection network solution. Compared with the traditional strip line (such as LTCC or microwave board) network, the loss is only 1 / 5 of it, effectively reducing the loss of the transceiver link and effectively improving the performance of the integrated sub-array.

[0018] 3) The upper layer of the composite interconnection layer is made of silicon material, and the lower layer is made of aluminum nitride material, both of which are materials with relatively high thermal conductivity. The two layers of materials are integrated together by large-area welding, and the heat transfer area is large. Compared with the interconnection layer made of traditional microwave plates, the thermal conductivity is two orders of magnitude higher.

[0019] 4) The composite interconnect layer's upper silicon layer has a thermal expansion coefficient of 2.5ppm, while the lower aluminum nitride layer, with a thermal expansion coefficient of 4.1ppm, is relatively close. This prevents significant stress from thermal expansion and contraction, leading to failure. This ensures good thermal compatibility, a key feature of large-area interconnects. The active subarray's silicon layer is integrated with the wafer's RF front end (silicon or other semiconductor materials), using the same or similar materials for good thermal compatibility. The aluminum nitride layer is soldered and integrated with a metal substrate (high-silicon aluminum or molybdenum copper, with a thermal expansion coefficient of approximately 4-7ppm). This close thermal expansion coefficient ensures excellent thermal compatibility and stability. This interconnect layer, using a composite silicon and aluminum nitride integration, offers excellent thermal compatibility both internally and with other external components, resulting in excellent thermal stability and significantly improving system environmental adaptability and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the active sub-array according to the first embodiment.

[0021] Figure 2 It is a cross-sectional schematic diagram of a two-level micro-coaxial network composite interconnection layer.

[0022] Figure 3 It is a planar schematic diagram of a two-level micro-coaxial network composite interconnection layer.

[0023] Figure 4 Schematic diagram of a three-level micro-coaxial network.

[0024] The meanings of the numbers in the figure are:

[0025] First connection point 1, wafer RF front end 2, composite interconnect layer 3, low-frequency connector 4, metal carrier 5, RF connector 6, via 7, second micro-coaxial network 8, third surface connection point 9, first surface connection point 10, second surface connection point 11, internal routing 12, gold wire 13, amplifier chip 14, welding surface 15, first micro-coaxial network 16, cavity 17, first welding point 18, second welding point 19, low-frequency network layer 20, micro-coaxial network layer 21. DETAILED DESCRIPTION

[0026] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0028] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.

[0029] Spatial relationship terms such as "under", "below", "beneath", "underneath", "above", "over", etc. can be used herein to describe the relationship of one element or feature shown in the figure with other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relationship terms also include different orientations of the device during use and operation. For example, if the device in the drawing is flipped, the element or feature described as "under other elements" or "beneath it" or "under it" will be oriented "above" the other elements or features. Therefore, the exemplary terms "under" and "beneath" can include both the upper and lower orientations. In addition, the device may also have other orientations (such as rotating 90 degrees or other orientations), and the spatial descriptors used herein are accordingly interpreted.

[0030] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In addition, in the following embodiments, "connection", if there is a transfer of electrical signals or data between the connected objects, should be understood as "electrical connection", "communication connection", etc.

[0031] As used herein, the singular forms "a", "an", and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprise / include" or "have" etc. specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0032] The composite interconnection layer on which the active subarray of the present invention is based is processed from a silicon-based radio frequency interconnection layer and a high-temperature aluminum nitride ceramic substrate, which can solve the problems of high integration density, high signal density and high heat flux density of millimeter-wave wafer subarrays. In the composite interconnection layer, the silicon layer integrates a radio frequency micro coaxial network to realize the distribution and transmission of radio frequency signals, and at the same time undertakes the vertical transmission and interconnection of low-frequency signals; the aluminum nitride layer integrates high-density traces to realize the distribution and transmission of power supply and control signals, and transitions to the surface of the silicon substrate layer through QFN pads and vertical vias; at the same time, the interconnection layer serves as a heat conduction carrier and can conduct the heat of the radio frequency front end to the metal carrier plate. The metal carrier plate is a high-aluminum silicon (or molybdenum copper) carrier plate, which is integrated with the interconnection layer by welding.

[0033] Embodiment 1

[0034] As Figure 1 shown, the upper surface of the composite interconnection layer 3 of the present invention is integrally interconnected with the wafer radio frequency front end 2 of the active subarray based on it through the first connection point 1 (BGA balls or QFNs in this embodiment). Generally, 4-16 wafer radio frequency front ends 2 can be integrated on the composite interconnection layer 3; the lower surface of the composite interconnection layer 3 is integrated with the metal carrier plate 5 by large-area welding. The low-frequency connector 4 and the radio frequency connector 6 are welded to the lower surface of the composite interconnection layer 3 and pass through the metal carrier plate 5, that is, the metal carrier plate 5 serves as the support and installation carrier for the composite interconnection layer 3, the low-frequency connector 4 and the radio frequency connector 6.

[0035] From the wafer radio frequency front end 2 to the metal carrier plate 5, the thermal expansion coefficients of the materials of the wafer radio frequency front end 2, the micro coaxial network layer 21, the low-frequency network layer 20 and the metal carrier plate 5 increase one by one. In this embodiment, the wafer radio frequency front end 2 is made of silicon or other semiconductor materials, and the metal carrier plate 5 is made of aluminum silicon or molybdenum copper, which has high thermal conductivity, a thermal expansion coefficient close to that of aluminum nitride material (or alumina), and high structural strength. It serves as the support and installation carrier for the composite interconnection layer and the connector at the same time, and completes functions such as heat export from the front end. The composite interconnection layer 3 completes the transmission and distribution of electrical signals (radio frequency, power supply, control, etc.) to the wafer radio frequency front end 2, completes the vertical transfer of heat flow from the wafer radio frequency front end 2 to the metal carrier plate 5, and at the same time serves as an intermediate insertion layer to complete the transition of the thermal expansion coefficient of the wafer radio frequency front end to the thermal expansion coefficient of the metal carrier plate to ensure thermal adaptation.

[0036] The specific implementation manner of the composite interconnection layer of the present invention is as Figure 2 and Figure 3 shown ( Figure 3 in which Figure 2The composite interconnect layer 3 includes a micro-coaxial network layer 21, a low-frequency network layer 20, an amplifier chip 14, a low-frequency connector 4, and an RF connector 6. The micro-coaxial network layer 21 is the upper layer and is connected to the wafer RF front end 2; the low-frequency network 20 is the lower layer and is connected to the metal carrier 5. The micro-coaxial network layer 21 and the low-frequency network 20 are interconnected and integrated through large-area welding or BGA. Figure 2 The serial number 15 represents the welding surface, 18 and 19 represent the first and second welding points respectively. The welding surface 15, the first welding point 18, and the second welding point 19 serve as signal transmission points at the same time.

[0037] In this embodiment, silicon material is selected for the upper layer and aluminum nitride (or aluminum oxide) material is selected for the lower layer. Both the upper and lower layer materials have high thermal conductivity. The two layers of material are integrated together through large-area welding, and the heat transfer area is large. Compared with the interconnection layer made of traditional microwave plates, the thermal conductivity coefficient is 2 orders of magnitude higher; the thermal expansion coefficient of the upper silicon material is close to that of the wafer RF front end, and the lower aluminum nitride material (or aluminum oxide) is close to the metal carrier plate, and the thermal expansion coefficients of the upper and lower layers of material are also close.

[0038] The low-frequency signal (power supply signal, control signal) is input by the low-frequency connector 4, distributed in the lower layer, transmitted to the first welding point 18 and the second welding point 19 through the internal routing 12, and then transmitted to the first surface connection point 10 and the second surface connection point 11 of the upper layer through the via 7 (TSV) in the upper layer, and then transmitted to the wafer RF front end 2 through BGA or QFN.

[0039] The micro-coaxial network includes a first micro-coaxial network 16 and a second micro-coaxial network 8. The first micro-coaxial network 16 and the second micro-coaxial network 8 each include three through-hole ports. The through-hole ports of the first micro-coaxial network 16 include a middle through-hole port located on its lower surface, a left through-hole port and a right through-hole port located on both sides of the middle through-hole; the through-hole ports of the second micro-coaxial network 8 include two through-hole ports located on its upper surface and one through-hole port located on its lower surface.

[0040] In this embodiment, there are two levels of micro-coaxial networks, including two second-level micro-coaxial networks 8 located on the upper side thereof and one first-level first micro-coaxial network 16 located below the second micro-coaxial network 8; the middle through-hole of the first-level first micro-coaxial network 16 is connected to the RF connector 6, and the left through-hole port and the right through-hole port of the first-level first micro-coaxial network 16 are respectively connected to the through-hole ports on the lower surface of different second-level second micro-coaxial networks 8.

[0041] The radio frequency signal is input through the radio frequency connector 6, distributed by the first micro coaxial network 16, and then returns to the surface on the side close to the lower layer of the upper layer; after being amplified by the amplification chip 14, it is input into the second micro coaxial network 8, and after being distributed and transmitted by the second micro coaxial network 8, it is output to the third surface connection point 9 on the upper layer and can be further transmitted to the wafer radio frequency front end 2; the signal interconnection between the amplification chip 14 and the micro coaxial network (including the first micro coaxial network 16 and the second micro coaxial network 8) is realized by gold wires 13 or flip chip bonding. When amplification is not required in the link design, the amplification chip 14 can be removed, and the two-stage micro coaxial networks 16 and 8 can be directly combined into one stage during substrate manufacturing, or can be directly bonded through gold wires 13.

[0042] On the upper surface of the low-frequency network layer 20, there is a cavity 17. The micro coaxial network 21 and the low-frequency network layer 20 are welded through the welding surface 15 to make the cavity 17 an airtight environment, protecting the amplification chip and enhancing the environmental adaptability and lifespan.

[0043] The first micro coaxial radio frequency network 16 and the second micro coaxial network 8 are processed on a silicon substrate through a silicon-based process. This network can distribute the total port input signal proportionally to other sub-ports, and the isolation between sub-ports is more than 20 dB, and the transmission loss is much lower than that of traditional strip lines.

[0044] Embodiment 2

[0045] The structural design of the composite interconnection layer in this embodiment is basically the same as that in Embodiment 1. The difference is that the micro coaxial network is further expanded from two stages in Embodiment 1 to three stages, forming a three-stage micro coaxial network topology, as Figure 4 shown.

[0046] At the corresponding position of the radio frequency connector 6, the low-frequency network layer 20 is designed with a round hole, and the radio frequency connector 6 passes through the low-frequency network layer 20 and is directly connected to the micro coaxial network layer 21. The low-frequency connector 4 is welded on the low-frequency network layer 20, generally by QFN surface mount welding.

[0047] The micro coaxial network includes a first micro coaxial network 16 and a second micro coaxial network 8. Both the first micro coaxial network 16 and the second micro coaxial network 8 include three through-hole ports. The through-hole ports of the first micro coaxial network 16 include a middle through-hole port on its lower surface, a left through-hole port and a right through-hole port on both sides of the middle through-hole; the through-hole ports of the second micro coaxial network 8 include two through-hole ports on its upper surface and one through-hole port on its lower surface.

[0048] The three - level micro - coaxial network described in this embodiment includes four second micro - coaxial networks 8 of the 3rd level located on its upper side, one first micro - coaxial network 16 of the 1st level and two first micro - coaxial networks 16 of the 2nd level located below the second micro - coaxial network 8. The first micro - coaxial networks 16 of the 1st to 2nd levels are connected in a binary - tree - type connection manner. Specifically, the left through - hole port and the right through - hole port of the first micro - coaxial network 16 of the 1st level are respectively connected to the middle through - hole ports of different first micro - coaxial networks 16 of the 2nd level. The middle through - hole of the first micro - coaxial network 16 of the 1st level is connected to the RF connector 6. The left through - hole port and the right through - hole port of the first micro - coaxial network 16 of the 2nd level are respectively connected to the through - hole ports on the lower surface of the second micro - coaxial network 8 of the 3rd level. The above - mentioned connection manner is as Figure 4 shown, Figure 4 where two second micro - coaxial networks 8 are omitted.

[0049] The composite interconnection layer and the active sub - array based on it proposed by the present invention can realize high - isolation, low - loss multi - port millimeter - wave signal distribution and transmission, as well as the transmission and distribution of control and power supply signals. It has the advantages of high integration, light weight, low profile, low loss, good thermal conductivity, etc. Specifically, it includes the following advantages:

[0050] 1) The composite interconnection layer adopts an overlapping integrated design of a silicon layer and an aluminum nitride layer. The upper layer is a planar silicon - based micro - coaxial network, and the lower layer is a planar aluminum nitride low - frequency network. The active chip is placed in the cavity 17 of the low - frequency network layer 20 and is interconnected with the micro - coaxial network by using gold wires or flip - chip bonding. The entire interconnection layer is in a flattened design. Through this integration method, the integration degree is greatly improved, and the profile height and weight of the interconnection layer are reduced.

[0051] 2) The RF signal is transmitted through the silicon micro - coaxial network. Compared with the traditional stripline (such as LTCC or microwave board) network, the loss is only 1 / 5 of it, effectively reducing the loss of the transceiver link and effectively improving the performance of the integrated sub - array.

[0052] 3) The upper layer of the composite interconnection layer is made of silicon material, and the lower layer is made of aluminum nitride material, both of which are materials with relatively high thermal conductivity. The two layers of materials are integrated together by large - area welding, and the heat - transfer area is large. Compared with the interconnection layer made of traditional microwave plates, the thermal conductivity is two orders of magnitude higher.

[0053] 4) The thermal expansion coefficient of the silicon material of the upper layer of the composite interconnection layer is 2.5ppm, and the thermal expansion coefficient of the lower layer material is aluminum nitride, which is 4.1ppm. The two are relatively close and will not cause failure due to large stress due to thermal expansion and contraction. Good thermal adaptation is the key to realizing large-area interconnection layers; the silicon layer is integrated with the wafer RF front end (silicon or other semiconductor materials), and the two materials are the same or similar, with good thermal adaptation; the aluminum nitride layer in the active sub-array is welded and integrated with the metal carrier (high silicon aluminum or molybdenum copper, with a thermal expansion coefficient of about 4-7ppm), with similar thermal expansion coefficients, good thermal adaptability and thermal stability; the interconnection layer using a composite integration of silicon and aluminum nitride has good thermal adaptation both internally and with the integration of other external components, and has good thermal stability, which can effectively improve the environmental adaptability and reliability of the system.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite interconnection layer, characterized in that, It includes a micro coaxial network layer (21) and a connected low-frequency network layer (20); a low-frequency connector (4) and a radio frequency connector (6) are arranged on the lower surface of the low-frequency network layer (20), and low-frequency signals and radio frequency signals are respectively input through the low-frequency connector (4) and the radio frequency connector (6) and then distributed through the low-frequency network layer (20) and the micro coaxial network layer (21), so as to complete the vertical transfer of heat flow from the micro coaxial network layer (21) to the low-frequency network layer (20); the micro coaxial network layer (21) includes several micro coaxial networks at N levels, and N is a positive integer; The micro coaxial network layer (21) includes a first micro coaxial network (16) and a second micro coaxial network (8). Both the first micro coaxial network (16) and the second micro coaxial network (8) include three through-hole ports. The through-hole ports of the first micro coaxial network (16) include a middle through-hole port on its lower surface, a left through-hole port and a right through-hole port on both sides of the middle through-hole. The through-hole ports of the second micro coaxial network (8) include two through-hole ports on its upper surface and one through-hole port on its lower surface. The N-level micro coaxial network includes second micro coaxial networks (8) of the Nth level on its upper side and one first micro coaxial network (16) of the first level, two first micro coaxial networks (16) of the second level,... first micro coaxial networks (16) of the nth level,... and second micro coaxial networks (8) of the (N - 1)th level below the second micro coaxial network (8), where n is a positive integer from 1 to N. The first micro coaxial networks (16) from the first level to the (N - 1)th level are connected in a binary tree connection manner. Specifically, the left through-hole port and the right through-hole port of the first micro coaxial network (16) of the (m - 2)th level are respectively connected to the middle through-hole ports of different first micro coaxial networks (16) of the (m - 1)th level. The middle through-hole of the first micro coaxial network (16) of the first level is connected to the RF connector (6). The left through-hole port and the right through-hole port of the first micro coaxial network (16) of the (N - 1)th level are respectively connected to the through-hole ports on the lower surface of different second micro coaxial networks (8) of the Nth level, where m is a positive integer from 3 to N. The material of the micro coaxial network layer (21) is silicon, the material of the low-frequency network layer (20) is aluminum nitride or alumina, and the micro coaxial network layer (21) and the low-frequency network layer (20) are connected by means of large-area welding; A cavity (17) is arranged on the upper surface of the low-frequency network layer (20), and an amplification chip (14) or a gold wire for connecting the micro coaxial network is placed in the cavity (17); after the micro coaxial network layer (21) and the low-frequency network layer (20) are welded through a welding surface (15), the cavity (17) becomes an airtight environment.

2. The composite interconnect layer according to claim 1, characterized in that The thermal expansion coefficient of the material of the low-frequency network layer (20) is greater than that of the material of the micro coaxial network layer (21).

3. The composite interconnect layer according to claim 1, wherein The micro coaxial networks are connected by an amplification chip (14).

4. The composite interconnect layer according to claim 1, wherein The micro coaxial networks are connected by gold wires.

5. The composite interconnect layer according to claim 1, characterized in that, Both the low-frequency network layer (20) and the micro coaxial network layer (21) are flat cuboids.

6. An active subarray, characterized in that, The active subarray is based on the composite interconnection layer according to any one of claims 1-5; the active subarray further includes a wafer radio frequency front end (2) and a metal carrier plate (5); the upper surface of the micro coaxial network layer (21) is connected to the wafer radio frequency front end (2), and the lower surface of the low-frequency network layer (20) is connected to the metal carrier plate (5); the low-frequency connector (4) and the radio frequency connector (6) are arranged on the lower surface of the low-frequency network layer (20) and pass through the metal carrier plate (5), and low-frequency signals and radio frequency signals are respectively input through the low-frequency connector (4) and the radio frequency connector (6), and after being distributed by the low-frequency network layer (20) and the micro coaxial network layer (21), they are transmitted to the wafer radio frequency front end (2), and thus the composite interconnection layer (3) completes the vertical transfer of heat flow from the wafer radio frequency front end (2) to the metal carrier plate (5).

7. The active subarray according to claim 6, wherein In the direction from the wafer radio frequency front end (2) to the metal carrier plate (5), the thermal expansion coefficients of the materials of the wafer radio frequency front end (2), the micro coaxial network layer (21), the low-frequency network layer (20), and the metal carrier plate (5) increase one by one.

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