A certain type of flat slot array antenna has a seven-layer structure, and the material is a certain anti-rust aluminum. Each part is precision machined by high-speed CNC milling. The two sides of the part are machined with complex grooves, the thickness of the structure varies from 0.5 to 2.0mm, and the typical precision of the part is 0.01mm. Needle welding connection between layers is required, all contact surfaces are needle welded, the brazing rate of the working waveguide brazing seam is basically 100%, there is no visible deformation, the flatness of the radiation surface is 0.1mm, and the brazing fillet is less than R0.2mm.

Due to the high requirements on the dimensional accuracy and welding rate of the flat slot array antenna, there are more than 100 brazing seams to be brazed. In addition, the aluminum alloy brazing process is poor and easy to deform, so brazing is difficult. The key to the brazing process is how to ensure a good welding rate and control the deformation to a minimum. The foreign seam array antenna generally adopts the salt bath brazing process, which is complicated in process and pollutes and consumes energy. This antenna is brazed by the vacuum brazing process.

The brazing filler metal is Ai-Si-Mg brazing filler metal with better vacuum brazing process, which is used in the form of 0.1mm thick foil. The brazing material is pre-processed into strips or shapes consistent with the brazing surface. The workpiece and the brazing material are chemically cleaned before brazing. According to the conventional cleaning process of aluminum alloy, they undergo degreasing, alkali cleaning and pickling passivation. Finally, they are cleaned with acetone and dried.

Use the energy storage spot welding machine to assemble and position the brazing material. After confirming that there is no leakage of the brazing material, the overall assembly of the antenna is carried out, and it is loaded into a special tooling and placed in an aluminum vacuum brazing furnace for brazing. Raise the temperature to 600°C at 10°C/min, keep warm, stop heating after the solder melts, and cool down to below 100°C with the furnace to take out the workpiece. Keep the vacuum degree not less than 2×10-2Pa during the heating and heat preservation process.

In order to ensure the necessary welding rate and dimensional accuracy, the design of the brazing tooling is very important. This time, the brazing adopts a flexible tooling with a delicate structure, which can ensure that the assembly gap occupied by the solder is effectively closed after the solder is melted. The pressing mechanism can follow and compensate the collapse of the structure after the solder is melted, and maintain a certain pressing force, which can effectively correct the original unevenness of the antenna parts, and control the pressure at the same time to avoid excessive pressure. Large and deformed, which not only ensures the quality of brazing, but also ensures the dimensional accuracy.