A packaging structure for a multi-channel weak signal detection system suitable for three-dimensional installation

Abstract

This invention relates to a packaging structure for a multi-channel weak signal detection system suitable for three-dimensional mounting. The packaging structure includes a substrate. From bottom to top, the top of the substrate has a first ring frame, a second ring frame, and a first cover plate; the bottom of the substrate has a third ring frame; the bottom of the third ring frame has a second cover plate; a flange is provided on the front and rear sides of the substrate, and a lead is provided on the left and right sides of the substrate; two flanges are located on the front and rear sides of the third ring frame, respectively; two lead are located on the left and right sides of the third ring frame, respectively. This invention employs a hybrid micro-assembly process based on bare chips, achieving double-sided assembly of components and highly reliable hermetically sealed packaging. The top surface of the packaging structure has three independent chambers, which can be used to assemble three channels of weak signal detection circuits respectively, thereby reducing inter-channel signal crosstalk caused by spatial electromagnetic radiation and external signal interference, and improving the detection accuracy of the circuit.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional system integration and packaging technology, specifically to a packaging structure for a multi-channel weak signal detection system suitable for three-dimensional installation. Background Art

[0002] With the increasing demand for military and civilian circuit systems, especially for weak signal detection systems, the requirements for integration, size, accuracy, and reliability are also rising. Traditional weak signal detection circuits are typically manufactured using printed circuit board (PCB) technology based on plastic-encapsulated devices. However, to meet these new demands, hybrid integrated packaging structures based on bare chips have gradually developed, mainly including the following two types:

[0003] (1) Metal packaging

[0004] This type of packaging enables single-sided component assembly and uses a ceramic substrate internally. However, its disadvantages include the relatively heavy metal casing and the fragile, easily broken glass insulators used.

[0005] (2) Ceramic packaging

[0006] This type of package can be a single-cavity or multi-cavity design, but it only supports single-sided component mounting. Furthermore, fabricating multi-cavity ceramic bodies involves complex processes, resulting in relatively low yields and significant difficulties in product repair. Additionally, this packaging method is not suitable for 3D mounting on system boards.

[0007] In summary, while these two packaging methods improve performance to some extent, they still face challenges in practical applications, such as assembly limitations, weight issues, material fragility, and production efficiency. Therefore, there is an urgent need to develop a packaging structure suitable for three-dimensional mounting of multi-channel weak signal detection systems. Summary of the Invention

[0008] The purpose of this invention is to provide a packaging structure suitable for three-dimensional mounting of a multi-channel weak signal detection system. This packaging structure overcomes the shortcomings of existing technologies. It not only employs a hybrid micro-assembly process based on bare chips to achieve double-sided micro-assembly of components on bare chips and highly reliable hermetically sealed packaging, effectively avoiding signal crosstalk between channels and external signal interference caused by spatial electromagnetic radiation, thus improving the detection accuracy of the circuit, but also enables the product to be mounted in a suspended, three-dimensional manner on the system PCB board. The multi-channel weak signal detection system using this packaging structure features small size, high accuracy, and flexible installation.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A packaging structure for a multi-channel weak signal detection system suitable for three-dimensional mounting is disclosed. The packaging structure includes a substrate. From bottom to top, a first ring frame, a second ring frame, and a first cover plate are sequentially arranged on the top of the substrate; a third ring frame is arranged on the bottom of the substrate; a second cover plate is arranged at the bottom of the third ring frame; a flange is provided on the front and rear sides of the substrate, and a lead-in leg is provided on the left and right sides of the substrate; the two flanges are located on the front and rear sides of the third ring frame, respectively; the two lead-in legs are located on the left and right sides of the third ring frame, respectively.

[0011] The first ring frame and the second ring frame have the same structure, both including a frame and multiple partition plates disposed in the frame, which divide the frame into multiple open mouths; the top of the substrate, the bottom of the first cover plate, the first ring frame, and the second ring frame form multiple sealed first chambers; the bottom of the substrate, the third ring frame, and the second cover plate form a sealed second chamber.

[0012] Furthermore, the first ring frame, the second ring frame, the third ring frame, the first cover plate, the second cover plate, the flange, and the lead leg are all made of metal.

[0013] Furthermore, the first ring frame and the substrate, as well as the second ring frame and the first ring frame, are all welded using AgCu eutectic high-temperature brazing.

[0014] Furthermore, the first ring frame is made of oxygen-free copper, the second ring frame is made of Kovar, the first cover plate is made of Kovar, and the first cover plate and the second ring frame are sealed with parallel seam welds.

[0015] Furthermore, the substrate is a multilayer high-temperature co-fired ceramic substrate; the multilayer high-temperature co-fired ceramic substrate is formed by stacking multiple AlN material green ceramic sheets with surface wiring and then firing them at high temperature; the surface of the green ceramic sheets is provided with metal conductors, and the material of the metal conductors is W; metallized through holes are provided between different layers of metal conductors of the substrate; the metallized through holes are filled with W paste.

[0016] Furthermore, the surface of the substrate is provided with pads; the bottom layer of the pads is made of metal W, and the top layer is made of Ni and Au; the pads are used for soldering components and the first ring frame and the third ring frame.

[0017] Furthermore, the number of wiring layers on the substrate is ≥10 layers, and the pitch of the leads is ≤1.27mm.

[0018] Furthermore, the first ring frame and the substrate, as well as the second ring frame and the first ring frame, are connected by AgCu eutectic high-temperature brazing to form a first chamber; the third ring frame is connected to the substrate by AgCu eutectic high-temperature brazing; the second cover plate is made of oxygen-free copper and is sealed with the third ring frame by laser seam welding.

[0019] Furthermore, the lead is made of Kovar and is connected to the substrate by AgCu eutectic high-temperature brazing; the welding surface of the lead to the system PCB protrudes 2mm from the sealing surface of the second cover plate.

[0020] Furthermore, the flange is made of Mo and is connected to the substrate by AgCu eutectic high-temperature brazing; the flange includes a longitudinal flange and a transverse flange disposed on one side of the top of the longitudinal flange; the transverse flange protrudes 2mm from the sealing surface of the second cover plate; the longitudinal flange has multiple notches; the transverse flange has multiple semi-circular through holes.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] The multi-channel weak signal detection system packaging structure suitable for three-dimensional installation described in this invention adopts a hybrid micro-assembly process based on bare chips, realizing double-sided assembly of components and highly reliable hermetic sealing. The top surface of this packaging structure has three independent chambers, which can be used to assemble three channels of weak signal detection circuits respectively, reducing signal crosstalk between channels caused by spatial electromagnetic radiation and external signal interference, thereby improving the detection accuracy of the circuit. The flange is not only used for welding or bolting the product to the system PCB board, but also serves as a heat dissipation channel. The flange and leads protrude 2mm from the bottom sealing surface, enabling overhead mounting on the system board. This overhead position can be used to install other components on the system PCB board, increasing the assembly density of the system PCB board. Because the structure and lead positions of this package are axially symmetrical in a planar coordinate system, when the output signal is a fully differential signal, distributing the differential signal processing circuit on the system PCB board at the bottom of the package allows for convenient and quick implementation of equal-length, coplanar, parallel, and short-distance routing of differential signal lines. This avoids the need for differential signal lines to cross layers and pass through vias during double-sided assembly of the system PCB board, which helps maintain signal integrity and avoid signal reflection. The multi-channel weak signal detection system using this packaging structure has the characteristics of small size, high precision, and flexible installation. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation in this invention. Figure 1 ;

[0024] Figure 2This is a schematic diagram of the packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation in this invention. Figure 2 ;

[0025] Figure 3 This is a schematic diagram of the packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation in this invention. Figure 3 ;

[0026] Figure 4 This is a schematic diagram of the structure of the multilayer high-temperature co-fired ceramic substrate in this invention.

[0027] in:

[0028] 100. Substrate; 101. Green ceramic tile; 102. Metal conductor strip; 103. Metal through hole; 104. Solder pad; 200. First ring frame; 300. Second ring frame; 400. Third ring frame; 500. First cover plate; 600. Second cover plate; 700. Flange; 701. Notch; 702. Semi-circular through hole; 800. Lead leg; 900. First chamber; 1000. Second chamber. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings:

[0030] like Figure 1 and Figure 2 The diagram illustrates a packaging structure for a multi-channel weak signal detection system suitable for three-dimensional mounting. This packaging structure includes a substrate 100. From bottom to top, the top of the substrate 100 is provided with a first ring frame 200, a second ring frame 300, and a first cover plate 500. The bottom of the substrate 100 is provided with a third ring frame 400, and the bottom of the third ring frame 400 is provided with a second cover plate 600. A flange 700 is provided on the front and rear sides of the substrate 100, and a lead leg 800 is provided on the left and right sides of the substrate 100. The two flanges 700 are located on the front and rear sides of the third ring frame 400, respectively. The two lead legs 800 are located on the left and right sides of the third ring frame 400, respectively. The first ring frame 200 and the second ring frame 300 have the same structure, both including a frame and multiple partition plates disposed within the frame, dividing the frame into multiple open mouths. The top of the substrate 100, the bottom of the first cover plate 500, and the first ring frame 200 and the second ring frame 300 form multiple sealed first chambers 900. The bottom of the substrate 100, the third ring frame 400, and the second cover plate 500 form a sealed second chamber 1000.

[0031] Conventional multi-cavity ceramic substrates are formed by stacking layer by layer during the punching and isostatic pressing processes in the green ceramic stage. Since components need to be assembled inside the cavities, there are relatively high requirements for the flatness of their bottoms, making the process control difficult. In addition, in order to improve the structural strength, the ceramic partitions between multiple cavities need to have a certain thickness. Moreover, as ceramics are non-electromagnetic shielding materials, the signal shielding effect is not good. According to the actual requirements of the circuit, the present invention can flexibly process a multi-cavity ceramic-metal integrated packaging shell structure that meets the electromagnetic shielding needs of the circuit by welding ring frames made of metal materials in different shapes such as I-shaped, 日-shaped, 目-shaped, and 田-shaped on the top and bottom welding interfaces of a planar multi-layer ceramic substrate. The packaging structure described in the present invention is commonly used for the weak signal detection of three accelerometers or three gyroscopes in an inertial navigation system. Therefore, three chambers are provided at the top of the substrate 100, and a weak signal detection circuit for one accelerometer or gyroscope is placed in each chamber. The heads and tails of the three chambers are respectively located at the leads 800 on the left and right sides of the substrate 100. The weak signal enters the circuit in the chamber from one side lead, and the signal after being processed by the circuit is output from the other side lead, realizing the shortest transmission path for signal input and output to the leads and reducing the external interference of the signal.

[0032] The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation described in the present invention belongs to the field of three-dimensional system integration packaging. This packaging structure is suitable for multi-channel weak signal detection systems and can achieve double-sided high-density hybrid integrated micro-assembly based on bare chips. The three independent first chambers 900 on the top surface of the substrate 100 can respectively assemble weak signal detection circuits for three channels to reduce the signal crosstalk between channels and external signal interference generated by space radiation. The second chamber 1000 on the back surface of the substrate 100 is used to install the common circuits of the weak signal detection circuits for three channels. The packaging structure described in the present invention can achieve highly reliable hermetic packaging by using brazing, laser seam welding, and parallel seam welding processes. The flange 700 therein is not only used for the mechanical fixation and heat dissipation of the product, but by raising the product and leaving an overhead position, it can be used to install other components on the system PCB board, realizing the three-dimensional installation of the components on the system PCB board to improve the assembly density, and can conveniently and quickly achieve equal length, coplanarity, parallelism, and short-distance routing of differential signals to maintain signal integrity. While achieving high-performance and highly reliable packaging of the multi-channel weak signal detection circuit, the present invention greatly reduces the product volume and realizes three-dimensional installation on the system PCB board, improving the flexibility of system layout and wiring and the component assembly density.

[0033] Preferably, the packaging structure of the multi-channel weak signal detection system of the present invention has three independent first chambers 900 distributed on the top surface and a second chamber 1000 disposed on the bottom surface. The first chamber 900 is formed by welding a first ring frame 200 made of oxygen-free copper and a second ring frame 300 made of Kovar material to a multilayer high-temperature co-fired ceramic substrate 100, and is hermetically sealed using a first cover plate made of Kovar material through parallel seam welding. The three independent first chambers 900 on the top surface can be used to assemble three channels of weak signal detection circuits to reduce signal crosstalk between channels and external signal interference caused by spatial electromagnetic radiation. The second chamber 1000 on the bottom surface houses the common circuit portion of the three channels.

[0034] Because the coefficient of thermal expansion of the high-temperature co-fired ceramic substrate 100 is approximately 4 × 10⁻⁶ -6 / ℃, the coefficient of thermal expansion of the second ring frame 300 is approximately 5.5×10. -6 If the two are directly welded at a temperature of / ℃, the difference in thermal expansion coefficients will cause the ceramic substrate 100 to bear excessive stress and crack under high and low temperature environments. Therefore, this invention uses a first ring frame 200 as a transition ring frame, utilizing the good ductility and plasticity of oxygen-free copper to absorb and reduce the stress borne by the ceramic substrate 100, thereby improving the reliability of the packaging structure. Furthermore, due to the high thermal conductivity of oxygen-free copper, the heat during brazing is more easily conducted to the welding interface, which is beneficial for the one-time brazing forming process of the high-temperature co-fired ceramic substrate 100 and the first ring frame 200, and the first ring frame 200 and the second ring frame 300, improving the reliability and airtightness of the welding surface, while also increasing the welding efficiency.

[0035] The multi-channel weak signal detection system packaging structure of the present invention has a second chamber 1000 on the bottom surface of the substrate 100. The second chamber 1000 is welded to the high-temperature co-fired ceramic substrate 100 by a third ring frame 400 made of oxygen-free copper, and the second cover plate 600 made of oxygen-free copper is used to achieve hermetic packaging by laser seam welding.

[0036] According to a preferred embodiment of the present invention, the first ring frame 200, the second ring frame 300, the third ring frame 400, the first cover plate 500, the second cover plate 600, the flange 700, and the lead leg 800 are all made of metal. The first ring frame 200 and the substrate 100, as well as the second ring frame 300 and the first ring frame 200, are all welded using AgCu eutectic high-temperature brazing. The welded surfaces have high airtightness and mechanical strength, and residual stress is reduced by controlling the brazing cooling temperature and atmosphere. The first cover plate 500 is made of Kovar and can be sealed with the second ring frame 300 using a highly reliable parallel seam weld, facilitating product rework. The first ring frame 200 effectively solves the problem of thermal expansion coefficient mismatch caused by direct welding of the substrate 100 and the second ring frame 300.

[0037] According to a preferred embodiment of the present invention, the substrate 100 is a multilayer high-temperature co-fired ceramic substrate. The multilayer high-temperature co-fired ceramic substrate has ≥10 wiring layers and a lead pitch ≤1.27mm. For example... Figure 4 As shown, the multilayer high-temperature co-fired ceramic substrate is made of AlN. It is formed by stacking multiple AlN green ceramic sheets 101 with surface wiring and then firing them at high temperature. Metal conductive strips 102, made of W, are disposed on the surface of each green ceramic sheet 101. Metallized vias 103 are provided between different layers of conductive strips in the multilayer high-temperature co-fired ceramic substrate; these vias are filled with W paste. AlN, with its high thermal conductivity and coefficient of thermal expansion similar to that of silicon-based bare chips, significantly reduces the thermal resistance of the package and improves the detection accuracy and reliability of chips and circuits. By controlling the process parameters such as AlN powder casting, isostatic pressing, and sintering, the substrate 100 achieves a flexural strength of 400 MPa and a surface flatness of 0.05 mm to meet micro-assembly requirements.

[0038] like Figure 4 As shown, the surface of the multilayer high-temperature co-fired ceramic substrate 100 is provided with pads 104; the bottom layer of the pads 104 is made of metal W, and the top layer is made of Ni and Au; the pads 104 are used for soldering components and the first ring frame 200 and the third ring frame 400. Each ring frame and flange is soldered to the multilayer high-temperature co-fired ceramic substrate using AgCu eutectic high-temperature brazing, providing a large temperature gradient space for component assembly.

[0039] like Figure 1 As shown, a first ring frame 200 and a second ring frame 300 are stacked and welded together to form three independent first chambers 900 on the top surface of the high-temperature co-fired ceramic substrate 100. After the components are assembled on the substrate 100 within the first chambers, a first cover plate 500 is used for highly reliable parallel seam welding sealing. The first ring frame 200, the second ring frame 300, and the first cover plate 500 provide protection and support for the internal circuits while greatly reducing signal crosstalk between channels and external signal interference caused by electromagnetic radiation from the weak signal detection circuits assembled in each chamber, thereby improving signal detection accuracy.

[0040] like Figure 1 As shown, the first ring frame 200 is made of oxygen-free copper, and the second ring frame 300 is made of Kovar. The first ring frame 200 and the multilayer high-temperature co-fired ceramic substrate 100, as well as the second ring frame 300 and the first ring frame 200, are connected by AgCu eutectic high-temperature brazing, forming three independent chambers 900. Figure 2As shown, the third ring frame 400 is made of oxygen-free copper and is welded to the multilayer high-temperature co-fired ceramic substrate 100 using AgCu eutectic high-temperature brazing. The second cover plate 600 is also made of oxygen-free copper and can be laser-welded to the third ring frame 400.

[0041] Since the thermal expansion coefficient of the high-temperature co-fired ceramic substrate 100 is approximately 4 × 10⁻⁶ -6 / ℃, the coefficient of thermal expansion of the second ring frame 300 is approximately 5.5×10. -6 If the two are directly welded at a temperature of / ℃, the difference in thermal expansion coefficients will cause the ceramic substrate 100 to bear excessive stress and crack under high and low temperature environments. Therefore, this invention uses a first ring frame 200 as a transition ring frame, utilizing the good ductility and plasticity of oxygen-free copper to absorb and reduce the stress borne by the ceramic substrate 100, thereby improving the reliability of the packaging structure. Furthermore, due to the high thermal conductivity of oxygen-free copper, the heat during brazing is more easily conducted to the welding interface, which is beneficial for the one-time brazing of the high-temperature co-fired ceramic substrate 100 to the first ring frame 200 and the first ring frame 200 to the second ring frame 300. By controlling the brazing cooling temperature and atmosphere to reduce residual stress, the reliability and airtightness of the welded surface are improved, and the welding efficiency is increased.

[0042] like Figure 1 and Figure 2 As shown, the lead 800 is made of Kovar and is welded to the multilayer high-temperature co-fired ceramic substrate 100 using AgCu eutectic high-temperature brazing. Figure 3 As shown, the soldering surface of the lead 800 to the system PCB board protrudes 2mm from the sealing surface of the second cover plate 600, enabling overhead mounting on the system PCB board. This overhead position can be used to mount other components on the system PCB board. The multi-channel weak signal detection system package structure described in this invention is symmetrical in structure and lead position in a planar coordinate system. When the output signal is a fully differential signal, the differential signal processing circuit is distributed on the system PCB board at the bottom of the package. This facilitates and quickly achieves equal length of differential signal lines and minimizes transmission distance. Simultaneously, it avoids the differential signal lines crossing layers and passing through vias when the system PCB board is assembled on both sides, which helps maintain signal integrity and avoid signal reflection.

[0043] like Figure 2As shown, the flange 700 is made of Mo and is welded to the high-temperature co-fired ceramic substrate 100 using AgCu eutectic high-temperature brazing. The flange 700 includes a longitudinal flange and a transverse flange located on one side of the top of the longitudinal flange; the transverse flange protrudes 2mm from the sealing surface of the second cover plate 600; the longitudinal flange has multiple notches 701; and the transverse flange has multiple semi-circular through holes 702. The notches 701 not only reduce product weight but also act as stress buffer grooves, alleviating the large stress transmission to the metal-ceramic welded parts during installation and fixing, thus improving the reliability of the packaging structure. The semi-circular through holes 702 allow for bolt installation and fixing to the system board. The flange 700 is used to weld or bolt the product to the system board and also acts as a heat dissipation channel, quickly conducting the heat generated by the circuit to the system PCB board, reducing product temperature rise and improving the stability of circuit parameters.

[0044] Because the lead 800 is thin and flexible, it can only be used for electrical connection and cannot be used for mechanical fixation of the package structure. Therefore, a flange 700 made of relatively high-strength metal is welded to the bottom surface of the package structure. The flange 700 can not only be directly soldered to the pads on the system PCB, but also be bolted to the system PCB through the semi-circular through-hole 702 on the flange 700. In addition, the flange 700 can also act as a heat dissipation channel, quickly conducting the heat generated by the circuit to the system PCB, reducing product temperature rise and improving the stability of circuit parameters.

[0045] The multi-channel weak signal detection system packaging structure suitable for three-dimensional installation described in this invention can be directly welded to the system PCB board via a 700 flange or bolted during application; for example... Figure 3 As shown, due to the 2mm height difference between the transverse flange face and the sealing face of the second cover plate 600, when this packaging structure is mounted on the system PCB board, there is a 2mm clearance between the system PCB board and the sealing face of the second cover plate 600. Components can be mounted on the system PCB board at this clearance position to increase the assembly density of the system PCB board. The metal flange soldered to the substrate serves both to solder or bolt the product to the system PCB board and as a heat dissipation channel, quickly transferring the heat generated by the circuit to the system PCB board, reducing product temperature rise and improving the stability of circuit parameters. Unlike the traditional board-level mounting method for component packaging, the flange and leads of this packaging structure protrude 2mm from the back sealing face, enabling the product to be mounted on the system PCB board above the surface. This clearance position can be used to mount other components on the system PCB board, increasing the assembly density of the system PCB board.

[0046] Because the package is axially symmetrical in terms of structure and lead position in a planar coordinate system, when the lead output signal is a fully differential signal, the differential signal processing circuit is distributed on the system PCB board in an overhead position. This allows for convenient and quick implementation of equal-length, coplanar, parallel, and short-distance routing of differential signal lines, avoiding the need for differential signal lines to cross layers and pass through vias when the system PCB board is assembled on both sides. This helps maintain signal integrity and avoid signal reflection.

[0047] In summary, this invention belongs to the field of three-dimensional system integration packaging, proposing a packaging structure suitable for three-dimensional mounting of a multi-channel weak signal detection system. This packaging structure enables double-sided high-density micro-assembly based on bare chips. The top three independent chambers can each assemble three channels of weak signal detection circuitry, reducing inter-channel signal crosstalk caused by spatial radiation and external signal interference. The bottom chamber houses the common circuitry for the three channels. Two cover plates achieve highly reliable hermetic sealing. The flange not only serves for mechanical fixation and heat dissipation but also elevates the product for three-dimensional mounting on the system PCB. This invention achieves high-performance, high-reliability packaging for multi-channel weak signal detection while significantly reducing the package size and enabling three-dimensional mounting on the system PCB, thus increasing the component assembly density of the system board.

[0048] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A packaging structure for a multi-channel weak signal detection system suitable for three-dimensional installation, characterized in that, The packaging structure includes a substrate (100); The top of the substrate (100) is provided with a first ring frame (200), a second ring frame (300) and a first cover plate (500) in sequence from bottom to top; the bottom of the substrate (100) is provided with a third ring frame (400); the bottom of the third ring frame (400) is provided with a second cover plate (600). A flange (700) is provided on the front and rear sides of the substrate (100), and a guide leg (800) is provided on the left and right sides of the substrate (100); the two flanges (700) are located on the front and rear sides of the third ring frame (400); the two guide legs (800) are located on the left and right sides of the third ring frame (400). The first ring frame (200) and the second ring frame (300) have the same structure, both including a frame and multiple partition plates disposed in the frame, which divide the frame into multiple open mouths; the top of the substrate (100), the bottom of the first cover plate (500), the first ring frame (200) and the second ring frame (300) form multiple sealed first chambers (900); the bottom of the substrate (100), the third ring frame (400) and the second cover plate (500) form a sealed second chamber (1000). The flange (700) includes a longitudinal flange and a transverse flange disposed on one side of the top of the longitudinal flange; the transverse flange protrudes 2 mm from the sealing surface of the second cover plate (600); the longitudinal flange has multiple notches (701); the transverse flange has multiple semi-circular through holes (702).

2. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 1, characterized in that, The first ring frame (200), the second ring frame (300), the third ring frame (400), the first cover plate (500), the second cover plate (600), the flange (700), and the pull leg (800) are all made of metal.

3. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 1, characterized in that, The first ring frame (200) and the substrate (100), and the second ring frame (300) and the first ring frame (200) are all welded by AgCu eutectic high-temperature brazing.

4. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 1, characterized in that, The first ring frame (200) is made of oxygen-free copper, the second ring frame (300) is made of Kovar, the first cover plate (500) is made of Kovar, and the first cover plate (500) and the second ring frame (300) are sealed by parallel seam welding.

5. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 1, characterized in that, The substrate (100) is a multilayer high-temperature co-fired ceramic substrate; the multilayer high-temperature co-fired ceramic substrate is formed by stacking multiple AlN material green ceramic sheets (101) with surface wiring and firing them at high temperature; the surface of the green ceramic sheet (101) is provided with metal conductor strips (102), and the material of the metal conductor strips (102) is W; metallized through holes (103) are provided between different layers of metal conductor strips (102) of the substrate; the metallized through holes (103) are filled with W paste.

6. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 1, characterized in that, The substrate (100) has pads (104) on its surface; the bottom layer of the pads (104) is made of metal W, and the top layer is made of Ni and Au; the pads (104) are used to solder components and the first ring frame (200) and the third ring frame (400).

7. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 1, characterized in that, The substrate (100) has ≥10 wiring layers, and the lead (800) has a pitch ≤1.27mm.

8. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 4, characterized in that, The first ring frame (200) and the substrate (100), and the second ring frame (300) and the first ring frame (200) are connected by AgCu eutectic high-temperature brazing to form a first chamber (900); the third ring frame (400) is connected to the substrate (100) by AgCu eutectic high-temperature brazing; the second cover plate (600) is made of oxygen-free copper and is sealed with the third ring frame (400) by laser seam welding.

9. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 4, characterized in that, The lead leg (800) is made of Kovar and is connected to the substrate (100) by AgCu eutectic high-temperature brazing; the welding surface of the lead leg (800) to the system PCB board protrudes 2mm from the sealing surface of the second cover plate (600).

10. The packaging structure of the multi-channel weak signal detection system suitable for three-dimensional installation according to claim 1, characterized in that, The flange (700) is made of Mo and is connected to the substrate (100) by AgCu eutectic high-temperature brazing.

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