Radar power amplifier channel assembly grounding welding method

Abstract

The invention discloses a radar power amplifier channel assembly grounding welding method which comprises the following steps: S1, cutting pieces according to the shape of a welding surface of each channel assembly, removing a surface oxide layer and cleaning; s2, the interior of the shell to be welded is cleaned, and after the channel assemblies and the soldering lugs are assembled to the shell, the channel assemblies and the soldering lugs are placed on a welding support in a vacuum vapor phase welding furnace in batches; s3, performing surface compaction on each channel assembly by adopting a single-body pressing block which has a preset weight and is consistent with the soldering lug in shape; s4, executing a vacuum vapor-phase welding process in a vacuum vapor-phase welding furnace, so that each channel assembly is grounded and welded with the shell, and the void ratio of a welding spot is not greater than 5% of the volume of the welding spot; and S5, the workpiece is taken out after welding is completed. The voidage of large-area welding of the power amplifier module is reduced, the welding reliability is guaranteed, heat dissipation faults caused by insufficient grounding after assembly welding are avoided, and meanwhile high-quality batch welding of assembly shells is met.

Description

Technical Field

[0001] The invention relates to surface mount technology (SMT), and in particular to a grounding welding method for a radar power amplifier channel component. Background Art

[0002] The power amplifier module is an important component of active phased array radar antennas and missile-borne radars. A set of radar antennas often has a large number of power amplifier modules. In order to achieve high-precision electrical performance requirements, the power amplifier module is required to have high reliability, high power, and low cost.

[0003] The power amplifier module includes a channel assembly and a shell. During the welding process of the channel assembly and the shell, due to the large welding area and the good fluidity of the solder under high temperature conditions, it is difficult to control the final state of the solder on the shell, and its welding quality cannot be guaranteed to meet the reliability of the grounding and electrical performance of the power amplifier module.

[0004] In order to solve the problem that the penetration rate of channel components during welding does not meet the national military standard requirements, resulting in insufficient heat dissipation and unreliable electrical performance, it is necessary to improve the existing welding method of power amplifier modules. Summary of the invention

[0005] The object of the present invention is to provide a grounding welding method for a radar power amplifier channel assembly to reduce the welding void rate, thereby meeting the reliability of the grounding and electrical performance of the power amplifier module.

[0006] To this end, the present invention provides a grounding welding method for radar power amplifier channel components, comprising the following steps: S1, cutting sheets according to the shape of the welding surface of each channel component, removing the surface oxide layer and cleaning; S2, cleaning the inside of the shell to be welded, assembling each channel component and the welding sheet to the shell, and placing them in batches on a welding bracket in a vacuum vapor phase welding furnace; S3, using a single-body pressing block with a predetermined weight and the same shape as the welding sheet to compact the surface of each channel component; S4, performing a vacuum vapor phase welding process in a vacuum vapor phase welding furnace to ground and weld each channel component to the shell, and making the porosity of the weld point not more than 5% of the volume of the weld point; S5, taking out the workpiece after welding is completed.

[0007] The method of the present invention reduces the void rate of large-area welding of components by reducing the thickness of the welding piece, reducing the number of welding blocks, improving the fluidity of the welding piece in a molten state by flux, accurately controlling the injection amount of the heating medium, the vacuum degree of the welding environment, and other process methods, thereby ensuring welding reliability and avoiding heat dissipation failures caused by insufficient grounding of the component after welding, thereby meeting high-quality batch production welding of the component shell.

[0008] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a flow chart of a grounding welding method for a radar power amplifier channel assembly of the present invention; Figure 2 is a schematic diagram of a radar power amplifier module housing of the present invention; Figure 3 is a three-dimensional diagram of a radar power amplifier module housing of the present invention; Figure 4 The shape of the channel assembly of the present invention is shown; Figure 5 The shape of the tin-lead solder piece of the present invention is shown; Figure 6 The shape of the one-piece compact of the present invention is shown. DETAILED DESCRIPTION

[0010] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0011] This welding method has undergone many tests. By adjusting the thickness of the soldering sheet, the amount of heating medium and the vacuum degree, the entire welding process and various process parameters of the welding method were finally determined to ensure that the voids in the welding joints are no larger than 5% of the volume of the solder joints, meeting the reliability of the component grounding and electrical performance.

[0012] Combined with reference Figures 1 to 6 The radar power amplifier channel assembly grounding welding method of the present invention includes the following steps S1-S5.

[0013] S1. Cut the welding pieces according to the shape of the welding surface of each channel component, grind the cut welding pieces, wipe them with alcohol after grinding, and apply flux after the alcohol is air-dried. Figure 4 As shown, the shape of the tin-lead solder piece is Figure 5 As shown, it is comb-shaped.

[0014] The soldering sheet is made of Sn63Pb37 with a thickness of 0.12mm, and the surface of the soldering sheet is evenly coated with medium-active rosin-type liquid flux.

[0015] S2. Use alcohol to clean the welding shell, assemble the welding components and welding pieces and place them on the welding bracket. According to the size of the welding bracket, 4 pieces can be placed in one furnace. Figure 2 and Figure 3 shown.

[0016] Preferably, the shell surface is plated with Ni3Au0.13-0.45 alloy to increase the weldability of the assembly. Figure 4 shown.

[0017] S3. Use a single-piece pressing block to make a pressing block of corresponding size according to the structural form of the channel assembly and compact it on the surface of the part. The shape of the single-piece pressing block is as follows: Figure 6 shown.

[0018] The pressing block used is a single-body pressing block, the quantity is 1 block, and the weight of a single pressing block is 1.5 kg.

[0019] S4. Place the assembled shell in a vacuum vapor phase welding furnace to perform vacuum vapor phase welding process and perform ground welding. Set the temperature, injection liquid volume, vacuum degree, and record the time.

[0020] The welding process is as follows: Preheating stage: injection liquid volume 400ml, preheating to 100℃, heating time 200s; The heating stage consists of the first and second stages. In the first stage, 200 ml of liquid was injected, the temperature was raised to 140°C, and the heating time was 78 seconds; in the second stage, 200 ml of liquid was injected, the temperature was raised to 175°C, and the heating time was 65 seconds; During the welding stage, the amount of liquid sprayed was 800 ml, the temperature was raised to 235 °C, and the heating time was 68 s; Vacuuming stage: Set the vacuum degree to 50mbar and the time to 12s. The melting point of the solder used is 183℃, and the welding temperature is set to 235℃.

[0021] The parameters of the above process stages are shown in the following table.

[0022] S5. After welding is completed, open the vacuum vapor phase furnace and take out the workpiece.

[0023] The above steps can be completed on a welding assembly line to achieve batch welding.

[0024] Compared with traditional infrared and hot air reflow soldering, the beneficial effects of the present invention are as follows: 1. The peak temperature during the welding stage is controllable. The peak temperature during the vacuum vapor phase welding stage is physically limited to the boiling point of the vapor phase liquid. The present invention uses a vapor phase liquid with a boiling point of 235°C, which is slightly higher than the melting point of tin-lead solder (183°C). The injection amount of the heating medium is precisely controlled, and the solder at the bottom of the component and the shell can be fully melted within 68 seconds without overheating. The peak temperature is uniform, consistent, and stable, eliminating the temperature difference between the component and the inside of the shell.

[0025] 2. Low stress. The interior of the vacuum vapor phase furnace is 360 degrees oAll-round heating, continuous and rapid heat exchange, avoid premature volatilization of flux. The temperature difference during the preheating process is smaller than that of traditional welding methods, and there is no peak temperature difference in the reflow zone. This uniformity can reduce the influence of stress. Under this condition, the bottom of the component is fully in contact with the shell through the gravity of the pressing block, which can effectively reduce the welding void rate between the component and the shell.

[0026] 3. Inert oxygen-free atmosphere. The density of the saturated vapor phase layer is much higher than that of air, and it is physically stratified with the air. The saturated vapor phase layer is an inert oxygen-free environment, which reduces the possibility of oxide and bubble formation. At the same time, under the action of the flux, the solder achieves the best wetting effect between the component and the shell, forming a good IMC layer and reducing the soldering void rate.

[0027] 4. Vacuum to remove bubbles. In the traditional welding process, the solder residue and gas cannot escape in time. After condensation, they are wrapped in the solder joint to form a void. However, the present invention sets a vacuum stage to timely extract the gas between the component and the shell before the solder is completely solidified, thereby reducing the void rate between the component and the shell.

[0028] The method of the present invention reduces the void rate of large-area welding of components by reducing the thickness of the welding piece, reducing the number of welding blocks, improving the fluidity of the welding piece in a molten state by flux, accurately controlling the injection amount of the heating medium, the vacuum degree of the welding environment, and other process methods, thereby ensuring welding reliability and avoiding heat dissipation failures caused by insufficient grounding of the component after welding, thereby meeting high-quality batch production welding of the component shell.

[0029] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A grounding welding method for a radar power amplifier channel assembly, characterized in that: The following steps are involved: S1. Cut the pieces according to the shape of the welding surface of each channel component, remove the surface oxide layer and clean it; S2. Clean the interior of the shell to be welded, assemble each channel assembly and welding sheet to the shell, and then place them in batches on a welding bracket in a vacuum vapor phase welding furnace; S3, using a single-body pressing block of predetermined weight and consistent with the shape of the welding piece to compact the surface of each channel component; S4. Performing a vacuum vapor phase welding process in a vacuum vapor phase welding furnace to ground and weld each channel component to the shell, and making the porosity of the welding point no greater than 5% of the volume of the welding point; S5. Take out the workpiece after welding is completed.

2. The grounding welding method for a radar power amplifier channel assembly according to claim 1, characterized in that: The welding process is as follows: Preheating stage: injection liquid volume 400ml, preheating to 100℃, heating time 200s; In the first stage, the injection volume was 200 ml, the temperature was raised to 140 °C, and the heating time was 78 s; In the second stage, the injection volume was 200 ml, the temperature was raised to 175 °C, and the heating time was 65 s; During the welding stage, the amount of liquid sprayed was 800 ml, the temperature was raised to 235 °C, and the heating time was 68 s; Vacuuming stage: set the vacuum degree to 50mbar and the time to 12s. The melting point of the selected solder sheet is 183°C, and the boiling point of the selected vapor phase liquid is 235°C.

3. The grounding welding method for a radar power amplifier channel assembly according to claim 1, characterized in that: The cut soldering pieces are polished, and then wiped with alcohol. After the alcohol is air-dried, soldering flux is evenly applied on the surface of the soldering piece, wherein the soldering flux is a medium-active rosin-type liquid soldering flux.

4. The grounding welding method for a radar power amplifier channel assembly according to claim 1, characterized in that: The solder sheet is Sn63Pb37, with a thickness of 0.12 mm and a melting point of 183.

5. The grounding welding method for a radar power amplifier channel assembly according to claim 1, characterized in that: The shell surface is plated with a Ni3Au0.13-0.45 alloy layer to increase the weldability of the channel component.

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