Microwave signal through-wall structure suitable for airtight cavity

Abstract

The invention discloses a microwave signal through-wall structure suitable for an airtight cavity. The microwave signal through-wall structure comprises an airtight box body and a through-wall transition printed board. The airtight box body comprises a box body and sealing cover plates, a partition wall is arranged in the middle of the box body and used for laser sealing of the two sealing cover plates and plays a role in cavity division, and a microwave circuit board is arranged in each cavity. A gap is formed in the middle of the partition wall and is drilled and milled from the bottom of the box body through a milling cutter, and the through-wall transition printed board penetrates through the gap and is placed in the box body. And the through-wall transition printed board and the microwave circuit board in the cavity are arranged in the box body by adopting a sintering process, and signal interconnection transmission is completed at the microstrip port in a mode of bonding an alloy wire. Compared with a traditional microwave signal up-and-down through-wall mode and an insulator interconnection mode, the microwave signal through-wall structure provided by the invention is simpler in required process, higher in assembly success rate, lower in material cost and suitable for large-scale production of micro-assembly circuits.

Description

Technical Field

[0001] The invention relates to a microwave signal wall-penetrating structure suitable for an airtight cavity, belonging to the technical field of microwaves. Background Art

[0002] The miniaturization and lightweight design of microwave modules are of great significance. Circuits based on micro-assembly technology are widely used due to their flexible design and high assembly density. Micro-assembly circuits use a large number of bare chips to reduce area and improve electrical performance, which puts forward higher requirements for airtightness.

[0003] When the circuit area is large, sealing the entire board will bring great hidden dangers to the airtightness. Generally, the method of sealing the cavity is adopted. At this time, a partition wall for sealing is left between the cavities. When it is necessary to transmit microwave signals between cavities, a printed circuit board is generally placed on the back of the box as a transition, and the front printed circuit board and the back printed circuit board are interconnected through radio frequency insulators. The microwave signal first passes through the insulator to the back, and then is transmitted to another insulator through the microstrip line on the back printed circuit board, and then transmitted to another cavity. This method realizes the transmission of microwave signals between the two cavities without affecting the airtightness of the sealing. However, this signal transmission structure requires additional insulators, which increases the material cost. At the same time, the sintering of the insulator has high requirements for the assembly process. Improper sintering of the insulator will increase the transmission loss and even the risk of short circuit. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a microwave signal wall-penetrating structure suitable for an airtight cavity, which has the characteristics of low material cost and simple assembly process.

[0005] The technical solution proposed by the present invention includes:

[0006] The microwave signal through-wall structure suitable for the airtight cavity comprises a box body 1, an upper sealing cover plate 2, a lower sealing cover plate 3, a microwave circuit board 6, a through-wall transition printed board 7, and a bonding gold wire 8. A partition wall 4 is provided in the middle of the box body 1, and a notch 5 is provided at the bottom thereof. The through-wall transition printed board 7 is placed at the bottom of the box body 1 through the notch 5. The through-wall transition printed board 7 and the microwave circuit board 6 in the cavity are installed in the box body by a sintering process, and the signal interconnection transmission is completed by a bonding gold wire 8 at the microstrip port.

[0007] Furthermore, the inner wall of the box body 1 is gold-plated for sintering the printed circuit board.

[0008] Furthermore, the thickness of the upper sealing cover plate 2 and the lower sealing cover plate 3 is 1 mm, which are used for sealing to ensure the airtightness of the box body.

[0009] Furthermore, the partition wall 4 and the box body 1 are integrally processed, and the upper surfaces are flush.

[0010] Furthermore, a notch 5 is provided at the bottom of the partition wall 4, which is formed by drilling and milling from the back of the box body using a milling cutter.

[0011] Furthermore, the through-wall transition printed circuit board 7 is a double-sided printed circuit board, and the microstrip line on the upper surface is plated with thick gold, and the thickness of the gold layer is greater than 2 um.

[0012] Furthermore, the through-wall transition printed circuit board 7 completes signal transmission with the microwave circuit board 6 at the microstrip port through the bonding wire 8.

[0013] Furthermore, the through-wall transition printed circuit board 7 has a compensation block at the port for compensating the inductance of the bonding wire, thereby improving high-frequency transmission performance.

[0014] Furthermore, two bonding gold wires (8) are used in parallel, the diameter of the gold wires is 25 um, and the spacing is 0.2 mm.

[0015] The beneficial effects of the present invention compared with the prior art are:

[0016] The microwave signal through-wall structure provided by the present invention uses a back-drilling method to mill a gap at the bottom of the partition wall for transition of the printed circuit board through the wall without affecting the sealing function of the partition wall. This structure has low mechanical processing difficulty, simple process required for circuit assembly, high assembly success rate, low material cost, and is suitable for large-scale production of micro-assembly circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a microwave signal wall-penetrating structure applicable to an airtight cavity according to the present invention;

[0018] Figure 2 The schematic diagram of the printed circuit boards of the present invention being interconnected by bonding gold wires.

[0019] Figure 1 Among them, 1 represents a box body, 2 represents an upper sealing cover plate, 3 represents a lower sealing cover plate, 4 represents a partition wall, 5 represents a gap at the bottom of the partition wall, 6 represents a microwave circuit board, 7 represents a through-wall transition printed circuit board, and 8 represents a bonding gold wire. DETAILED DESCRIPTION

[0020] The present invention is further explained below in conjunction with the accompanying drawings and preferred embodiments.

[0021] like Figure 1 and Figure 2 As shown, the microwave signal wall-penetrating structure applicable to the airtight cavity provided by the embodiment of the present invention mainly comprises: a box body, a sealing cover plate, a printed circuit board and a bonding gold wire;

[0022] The micro-assembly process of the microwave signal through-wall structure suitable for the airtight cavity is as follows: first, the SMT surface mounting process is used to complete the surface mounting of the packaged device on the microwave circuit board 6, and then the microwave circuit board 6 and the through-wall transition printed board 7 are soldered to the inside of the box body 1, and then the conductive glue is used to complete the bonding of the bare chip on the microwave circuit board 6, and then the bonding process is used to complete the gold wire interconnection between the bare chip and the microwave circuit board 6 and the through-wall transition printed board 7, and finally the laser sealing process is used to seal the upper sealing cover plate 2 and the lower sealing cover plate 3 on the box body to complete the airtight assembly of the entire box body.

[0023] In an optional embodiment of the present invention, the box body 1 is made of 6063 aluminum alloy, the upper sealing cover plate 2 and the lower sealing cover plate 3 are made of 4047 aluminum alloy, and the thickness of the upper and lower sealing cover plates is 1 mm.

[0024] In an optional embodiment of the present invention, the through-wall transition printed circuit board 7 and the microwave circuit board 6 in the cavity are installed in the box body at the same temperature gradient by using a sintering process, and the solder used is 63Sn37Pb.

[0025] In an optional embodiment of the present invention, the partition wall 4 and the box body 1 are integrally processed, the upper surface is flush, and the width of the partition wall is 4 mm.

[0026] In an optional embodiment of the present invention, the partition wall 4 has a notch 5 at the bottom, which is drilled and milled from the back of the box body using a milling cutter, and the notch width is 3 mm and the height is 2 mm.

[0027] In an optional embodiment of the present invention, the through-wall transition printed circuit board 7 is a double-sided printed circuit board, the material selected is Rogers3003C, the microstrip line width is 0.6mm, and the upper surface microstrip line is plated with thick gold, and the thickness of the gold layer is greater than 2um.

[0028] In an optional embodiment of the present invention, the through-wall transition printed circuit board 7 completes signal transmission with the microwave circuit board 6 through a bonding wire 8 at the microstrip port. The length of the bonding wire should be as short as possible to reduce the influence of parasitic inductance on microwave performance.

[0029] In an optional embodiment of the present invention, the through-wall transition printed circuit board 7 has a compensation block at the port for compensating for the inductance of the bonding wire to improve the high-frequency transmission performance. The size of the compensation block should be determined through full-wave simulation optimization based on the actual printed circuit board material used. In this example, the size of the compensation block is 0.2mm×0.2mm.

[0030] The above description is only a preferred example of the present invention and is not intended to limit the present invention. Any size modification, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A microwave signal wall-penetrating structure suitable for an airtight cavity, characterized in that: The structure comprises a box body (1), an upper sealing cover plate (2), a lower sealing cover plate (3), a microwave circuit board (6), a through-wall transition printed board (7), and a bonding gold wire (8); a partition wall (4) is provided in the middle of the box body (1), and a notch (5) is provided at the bottom thereof; the through-wall transition printed board (7) passes through the notch (5) and is placed at the bottom of the box body (1); the through-wall transition printed board (7) and the microwave circuit board (6) in the cavity are installed in the box body by using a sintering process, and a bonding gold wire (8) is used at a microstrip port to complete signal interconnection and transmission.

2. The microwave signal wall-penetrating structure suitable for an airtight cavity according to claim 1, characterized in that: The inner wall of the box body (1) is gold-plated and is used for sintering printed circuit boards.

3. The microwave signal wall-penetrating structure suitable for an airtight cavity according to claim 1, characterized in that: The thickness of the upper sealing cover plate (2) and the lower sealing cover plate (3) is 1 mm, and they are used for sealing to ensure the airtightness of the box body.

4. The microwave signal wall-penetrating structure suitable for an airtight cavity according to claim 1, characterized in that: The partition wall (4) and the box body (1) are integrally processed and have flush upper surfaces.

5. The microwave signal wall-penetrating structure suitable for an airtight cavity according to claim 4, characterized in that: The bottom of the partition wall (4) is provided with a notch (5), which is formed by drilling and milling from the back of the box body using a milling cutter.

6. The microwave signal wall-penetrating structure suitable for an airtight cavity according to claim 1, characterized in that: The through-wall transition printed board (7) is a double-sided printed board, and the microstrip line on the upper surface is plated with thick gold, and the thickness of the gold layer is greater than 2 μm.

7. The microwave signal wall-penetrating structure suitable for an airtight cavity according to claim 6, characterized in that: The through-wall transition printed circuit board (7) completes signal transmission with the microwave circuit board (6) at the microstrip port through a bonding gold wire (8).

8. The microwave signal wall-penetrating structure suitable for an airtight cavity according to claim 6, characterized in that: The through-wall transition printed board (7) has a compensation block at the port for compensating the inductance of the bonding wire, thereby improving high-frequency transmission performance.

9. The microwave signal wall-penetrating structure suitable for an airtight cavity according to claim 7, characterized in that: Two bonding gold wires (8) are used in parallel, the diameter of the gold wires is 25 um, and the spacing is 0.2 mm.

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