A heterogeneous microstrip board soldering method of a filter power division network

Abstract

The application discloses a welding method of a heterogeneous microstrip plate of a filter power division network, and relates to the technical field of radar electronic functional components.The method comprises the following steps: step one, producing filter microstrip plate welding pieces and power division microstrip plate welding pieces through numerical control laser cutting;step two, tin plating and gold removing are performed on the bottom of the first power division microstrip plate and the second power division microstrip plate, and the first power division microstrip plate and the second power division microstrip plate are placed in the middle of a special tool and leveled while hot;step three, flux is uniformly brushed on the cavity welding surface of the shell, and the filter microstrip plate welding pieces and the power division microstrip plate welding pieces are installed.The application guides directional flow of liquid solder through tin amount control hole design, avoids liquid solder flowing into an air cavity and thus generating excess substances, effectively solves the uncontrollable phenomenon of molten soldering tin in the welding process, effectively avoids negative effects caused by excess substances such as tin balls and tin residues, and the process technology state is stable, and the welding quality is reliable.

Description

Technical Field

[0001] This invention relates to the field of radar electronic functional components technology, and specifically to a method for welding heterogeneous microstrip boards for filtering power dividers. Background Technology

[0002] With the rapid development and widespread adoption of modern microwave wireless communication technology, passive power dividers are playing an increasingly important role in RF circuits and antenna feeding systems. Traditional passive networks often directly cascade several single-function microwave devices, which is detrimental to reducing manufacturing costs, circuit size, and mismatch losses. Furthermore, the higher the operating bandwidth of the devices, the more difficult it is to adjust the cascade matching. To meet the demands of miniaturization, integration, broadband, and multifunctionality in electronic devices, reduce the size burden of circuits, and increase the matching degree of cascaded circuits, filters, as important components of the microwave front end, integrate filtering functions into power dividers or antennas and design them collaboratively. This approach offers advantages such as fewer components, lower impedance mismatch and losses, smaller system size, higher overall efficiency, and lower cost.

[0003] Compared to ordinary power dividers, this new power divider network, which integrates filtering functionality, incorporates a filtering microstrip board in its structure. The substrate material and thickness differ from the power divider microstrip board, and an air cavity is added to the shell structure corresponding to the filtering microstrip board area. Therefore, the overall structure of this novel filtering power divider network is more complex, with a higher assembly density per unit volume. It also presents high-standard and diverse welding quality requirements, necessitating precise control of the liquid solder flow. The liquid solder must achieve good wetting and spreading at the welding area while preventing it from flowing into non-welding areas. Traditional temperature gradient welding or high-precision low-temperature brazing processes cannot guarantee the required welding accuracy, diverse welding quality, reliability, and stability. Therefore, a heterogeneous, large-area microstrip board welding technology is urgently needed to obtain a highly efficient and reliable filtering power divider network. Summary of the Invention

[0004] The purpose of this invention is to provide a method for welding heterogeneous microstrip boards for filtering power dividers, which solves the problem that existing manufacturing methods cannot guarantee uniform heating of microstrip boards of different thicknesses and precise control of liquid solder flow for microwave components with uneven thicknesses and irregular structures.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution, and the present invention includes the following steps:

[0006] Step 1: Produce filter microstrip board solder pads and power divider microstrip board solder pads using CNC laser cutting;

[0007] Step 2: Tin-plating and gold removal are performed on the bottom of both the first and second power division microstrip boards, and the first and second power division microstrip boards are placed in the middle of a special tooling and leveled while still hot.

[0008] Step 3: Apply flux evenly to the cavity welding surface of the shell, and install the filter microstrip board solder pads and the power divider microstrip board solder pads;

[0009] Step 4: Install the first power divider microstrip board, the filter microstrip board, and the second power divider microstrip board into the cavity of the housing;

[0010] Step 5: Install the split shaping fixtures and place them on top of the first power divider microstrip board, the filter microstrip board, and the second power divider microstrip board;

[0011] Step 6: Integrate the shell, the first power divider microstrip board, the filter microstrip board and the second power divider microstrip board of the loaded split shaping fixture;

[0012] Step 7: Use X-Ray to inspect the weld quality;

[0013] Step 8: Remove the split shaping fixture and clean the microstrip board after soldering using solvent.

[0014] Preferably, in step one, the filter microstrip board solder pads are processed using a serrated shrinkage method, and the area of ​​the solder pads is designed to be 80-85% of the actual welding surface area.

[0015] Preferably, the filter microstrip board has solder quantity control holes and vent holes; wherein the solder quantity control holes are metallized holes or semi-metallized holes formed by back drilling, the solder quantity control holes are in two rows, and the diameters of the two rows of solder quantity control holes are equal, and the distance between two adjacent solder quantity control holes is less than or equal to the hole diameter; the vent holes are unmetallized through holes.

[0016] Preferably, in step two, the bottom of the first and second power-dividing microstrip boards are tinned and gold-removed using a soldering iron and a heating platform.

[0017] Preferably, the inner bottom of the cavity has a first power-dividing microstrip board welding surface, a filter microstrip board welding surface, and a second power-dividing microstrip board welding surface.

[0018] Preferably, in step five, the welding surfaces of the filter microstrip board, the first power divider microstrip board, and the second power divider microstrip board are all partially silver-plated with aluminum.

[0019] Preferably, in step five, the split-type shaping fixture includes three pressing blocks, the shapes of which correspond to the filter microstrip board, the first power divider microstrip board, and the second power divider microstrip board, respectively.

[0020] Preferably, the three pressing blocks of the split-type shaping tool are made of stainless steel, aluminum alloy, or chrome-plated brass alloy or copper.

[0021] Preferably, in step six, integrated welding is performed according to the brazing temperature profile, and the brazing includes: low-temperature vacuum brazing and vacuum vapor phase welding.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. By using a solder quantity control hole design, the liquid solder is guided to flow in a specific direction, preventing the liquid solder from flowing into the air cavity and generating excess material. This effectively solves the problem of uncontrollable molten solder during the welding process and avoids the negative impact of the formation of excess material such as solder balls and solder dross. The process technology is stable and the welding quality is reliable.

[0024] 2. The vent design ensures that the internal and external pressure difference of the filter microstrip board is consistent and the stress is uniform during the heating / cooling process, thus avoiding the loss of control of solder flow due to gas compression.

[0025] 3. The separate shaping tooling design for dissimilar materials provides the pressure required for welding microstrip boards, achieving the purpose of eliminating air. At the same time, it solves the problem of obtaining different welding temperatures and heat during the welding process of dissimilar microstrip boards with uneven thickness and different materials, and achieves precise control of the flow of liquid solder.

[0026] 4. Precise quantitative design of welding pieces: adopting a serrated material reduction process and combining the welding characteristics of low-temperature brazing, the prefabricated welding pieces are designed to ensure that the area of ​​the welding piece accounts for 80-85% of the actual welding surface area, thereby achieving quantitative control of the solder and obtaining high-penetration welding quality.

[0027] 5. The refined brazing temperature profile design ensures that the microstrip board is within a suitable and controllable temperature range in every step from heating to welding to cooling, further enhancing the precise control of the solder and the reliability of welding, and achieving one-time welding. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the filtering power divider network structure of the present invention;

[0029] Figure 2 This is a schematic cross-sectional view of the filtering power dividing network of the present invention;

[0030] Figure 3 This is a schematic diagram of the housing of the present invention;

[0031] Figure 4 This is a schematic diagram of the filter microstrip board structure of the present invention;

[0032] Figure 5 This is a schematic diagram of the solder pad structure of the filter microstrip board of the present invention;

[0033] Figure 6 This is a brazing temperature curve of the heterogeneous large-area microstrip board of the present invention;

[0034] Figure 7 This is a schematic diagram of the split-type shaping tooling structure of the present invention.

[0035] The numbers in the image represent:

[0036] 1-Housing; 2-First power divider microstrip board; 3-Filter microstrip board; 4-Second power divider microstrip board; 5-Filter microstrip board solder pad; 11-First power divider microstrip board soldering surface; 12-Filter microstrip board soldering surface; 13-Air cavity; 14-Second power divider microstrip board soldering surface; 31-Positioning pin hole; 32-Screw mounting hole; 33-Tin quantity control hole; 34-Ventilation hole. Detailed Implementation

[0037] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0038] Example 1

[0039] This embodiment provides a technical solution: a method for welding heterogeneous microstrip boards for a filter power divider network, referring to... Figure 1 This includes the following steps:

[0040] Step 1: Produce the filter microstrip board solder pad 5 and the power divider microstrip board solder pad by CNC laser cutting;

[0041] The filter microstrip board solder pad 5 adopts a sawtooth shrinkage process, and the area of ​​the solder pad is designed to be 80-85% of the actual welding surface area, so as to realize the quantitative control of the solder and obtain welding quality with high penetration rate.

[0042] Step 2: Tin-plating and gold removal are performed on the bottom of both the first power dividing microstrip board 2 and the second power dividing microstrip board 4, and the first power dividing microstrip board 2 and the second power dividing microstrip board 4 are placed in the middle of a special tooling and leveled while hot.

[0043] The bottom of the first power-dividing microstrip board 2 and the second power-dividing microstrip board 4 are de-tinned using a soldering iron and a heating platform.

[0044] Step 3: Apply flux evenly to the cavity welding surface of housing 1, and install the filter microstrip board solder pad 5 and the two power divider microstrip board solder pads into the corresponding positions in the cavity;

[0045] The inner bottom of the cavity has a first power-dividing microstrip board welding surface 11, a filter microstrip board welding surface 12, and a second power-dividing microstrip board welding surface 14; the two power-dividing microstrip board welding pieces correspond to the first power-dividing microstrip board welding surface 11 and the filter microstrip board welding surface 12, respectively, and the filter microstrip board welding piece 5 corresponds to the filter microstrip board welding surface 12.

[0046] In this embodiment, the depth of the first power divider microstrip board welding surface 11 and the second power divider microstrip board welding surface 14 is 3.76 mm; the depth of the filter microstrip board welding surface 12 is 3.25 mm; the filter microstrip board welding surface 12, the first power divider microstrip board welding surface 11 and the second power divider microstrip board welding surface 14 are all locally aluminum-plated with silver.

[0047] Step 4: Install the first power divider microstrip board 2, the filter microstrip board 3, and the second power divider microstrip board 4 into the cavity of the housing 1;

[0048] The filter microstrip board 3 has solder quantity control holes 33 and ventilation holes 34. Based on meeting the electrical performance requirements proposed by the telecommunications institute, the solder quantity control holes 33 designed around the filter microstrip board 3 above the air cavity 13 are metallized holes or semi-metallized holes formed by back drilling, and must be plating-compatible.

[0049] The solder quantity control holes 33 have two rows, and the diameters of the two rows of solder quantity control holes 33 are equal. The distance between two adjacent solder quantity control holes 33 is less than or equal to the hole diameter. The design of the solder quantity control holes 33 guides the directional flow of liquid solder and prevents liquid solder from flowing into the air cavity 13 and thus generating excess material.

[0050] The vent 34 is a through-hole and is not metallized. There may be one or more vent holes. When there are multiple vent holes 34, they are evenly distributed in the middle area of ​​the filter microstrip board above the air cavity. The design of the vent holes 34 ensures that the internal and external pressure difference of the filter microstrip board 3 is consistent and the stress is uniform during the heating / cooling process, thus avoiding the loss of control of solder flow due to gas compression.

[0051] Step 5: Install the split shaping fixtures and place them on top of the first power divider microstrip board 2, the filter microstrip board 3, and the second power divider microstrip board 4 respectively;

[0052] The split-type shaping fixture includes three pressure blocks, the shapes of which correspond to the filter microstrip board 3, the first power divider microstrip board 2, and the second power divider microstrip board 4, respectively. The three pressure blocks of the split-type shaping fixture are made of stainless steel, aluminum alloy, or chrome-plated brass alloy or copper. In this embodiment, it is composed of two aluminum alloy blocks and one brass alloy block, wherein the fixture above the filter is made of brass alloy.

[0053] Step 6: Perform integrated welding on the shell 1, the first power distribution microstrip board 2, the filter microstrip board 3 and the second power distribution microstrip board 4 of the loaded split shaping fixture;

[0054] By performing integrated welding based on the brazing temperature profile, the precision control of the solder and the reliability of the welding are enhanced. Brazing includes welding methods that meet vacuum conditions, such as low-temperature vacuum brazing and vacuum vapor phase welding. This embodiment selects the vacuum vapor phase welding method, which has a shorter overall production time.

[0055] Step 7: Use X-Ray to inspect the weld quality;

[0056] Step 8: Remove the split shaping fixture and clean the microstrip board after soldering using solvent.

[0057] This embodiment achieves precise control of liquid solder, meeting diverse and high-standard welding quality requirements. The process technology is stable, the welding quality is reliable, the solder penetration rate reaches over 90%, and the yield is increased to 99%. The performance of the resulting novel filter power divider network meets the design requirements. These results verify the correctness of the design, process consistency, performance compliance, and reliability of this method. This method has broad application prospects in the development of power divider networks for fusion filters.

[0058] Example 2

[0059] This embodiment uses a filter power divider network prepared according to the method in Embodiment 1, such as... Figure 1-2 As shown, the filtering power divider network includes a housing 1, a first power divider microstrip board 2, a filtering microstrip board 3, and a second power divider microstrip board 4, wherein the housing is made of 5A06 aluminum alloy.

[0060] like Figure 2-3 As shown, the housing 1 is a single-sided cavity housing, and the shape of the cavity matches the shape of the power divider network microstrip board. The power divider network microstrip board is welded to the inside of the cavity. The power divider network microstrip board includes a first power divider microstrip board 2, a filter microstrip board 3, and a second power divider microstrip board 4.

[0061] The inner bottom of the cavity has a first power-dividing microstrip board welding surface 11, a filter microstrip board welding surface 12, and a second power-dividing microstrip board welding surface 14; the depth of the first power-dividing microstrip board welding surface 11 and the second power-dividing microstrip board welding surface 14 is 3.76 mm, and the depth of the filter microstrip board welding surface 12 is 3.25 mm; all three welding surfaces are partially silver-plated with aluminum to increase solderability; the filter microstrip board welding surface 12 has a downwardly recessed air cavity 13 with a depth of 4.12 mm;

[0062] The first power divider microstrip board 2 and the second power divider microstrip board 4 both use Taconic dielectric substrate TLY with a thickness of 0.762mm, a relative permittivity of 2.2, and a loss tangent of 0.0009; the filter microstrip board 3 uses Rogers RT5880 dielectric substrate with a thickness of 0.254mm, a relative permittivity of 2.2, and a loss tangent of 0.0009.

[0063] like Figure 4 As shown, the filter microstrip board 3 has two rows of solder quantity control holes 33, two positioning pin holes 31, six screw mounting holes 32 and six vent holes 34, among which the solder quantity control holes 33 are metallized holes.

[0064] like Figure 5 As shown, the filter microstrip board solder pad 5 adopts a sawtooth shrinkage treatment method. The solder pad is precisely designed according to the welding characteristics of low temperature brazing, and the area of ​​the solder pad accounts for 82% of the actual welding surface area.

[0065] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method of soldering a heterogeneous microstrip board of a filter power division network, characterized by: The method comprises the following steps: Step 1: producing filter microstrip plate soldering sheet and power division microstrip plate soldering sheet through numerical control laser cutting; Step 2: tin soldering and gold removing on the bottom of the first and second power division microstrip plates, and placing the first and second power division microstrip plates in the middle of the special tool and leveling while hot; Step 3: uniformly brushing the flux on the cavity welding surface of the shell, and installing the filter microstrip plate soldering sheet and the power division microstrip plate soldering sheet; Step 4: installing the first power division microstrip plate, the filter microstrip plate and the second power division microstrip plate into the cavity of the shell; Step 5: installing the split-shaped molding tool on the top of the first power division microstrip plate, the filter microstrip plate and the second power division microstrip plate; Step 6: integrally welding the shell, the first power division microstrip plate, the filter microstrip plate and the second power division microstrip plate loaded with the split-shaped molding tool; Step 7: detecting the welding quality by using X-Ray; Step 8: removing the split-shaped molding tool, and cleaning the microstrip plate after welding by using solvent.

2. The method of claim 1, wherein the method further comprises: In step 1, the filter microstrip plate soldering sheet adopts sawtooth-shaped material reduction processing mode, and the area of the soldering sheet is designed as 80-85% of the actual welding surface area.

3. The method of claim 1, wherein the method further comprises: The filter microstrip plate is provided with tin amount control holes and air holes; the tin amount control holes are metallized holes or half-metallized holes formed by back drilling, the tin amount control holes have two rows, the diameters of the two rows of tin amount control holes are equal, and the distance between adjacent two tin amount control holes is less than or equal to the hole diameter; the air holes are through holes without metallization.

4. The method of claim 1, wherein the method further comprises: In step 2, the first and second power division microstrip plates are tin soldered and gold removed on the bottom by using electric iron and heating platform.

5. The method of claim 1, wherein the method further comprises: The inner bottom of the cavity is provided with a first power division microstrip plate welding surface, a filter microstrip plate welding surface and a second power division microstrip plate welding surface.

6. The method of claim 5, wherein the soldering is performed by using a soldering iron. In step 5, the filter microstrip plate welding surface, the first power division microstrip plate welding surface and the second power division microstrip plate welding surface are locally plated with silver.

7. The method of claim 1, wherein the method further comprises: In step 5, the split-shaped molding tool comprises three pressing blocks, and the shapes of the three pressing blocks correspond to the filter microstrip plate, the first power division microstrip plate and the second power division microstrip plate respectively.

8. The method of claim 7, wherein the soldering is performed by using a soldering iron. The materials of the three pressing blocks of the split-shaped molding tool are stainless steel, aluminum alloy or brass alloy or purple copper with surface chrome plating.

9. The method of claim 1, wherein the method further comprises: In step 6, the integrally welding is performed according to the brazing temperature curve, and the brazing includes low-temperature vacuum brazing and vacuum vapor phase welding.

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