This study aims to investigate the application of powder pressing technology in the preparation of composite solder sheets and to research the effects of different pressing process parameters on the mechanical properties

microstructure

and brazing performance of composite solder sheets. SAC305 alloy powder and self-developed flux were pre-mixed and then pressed into composite solder sheets using powder pressing technology. A three-level three-factor orthogonal experiment was designed to analyze the effects of pressure

pressing temperature

and pressing time on the properties of the composite solder sheets. The results show that pressure is the most significant pressing parameter affecting the properties of the composite solder sheets. When the pressure is insufficient

the microstructure of the composite solder sheet exhibits distinct interface distinctions between tin alloy powder particles

with a small powder deformation and a high porosity. With increasing pressure

the powder undergoes obvious deformation

the interfaces become blurred

and the porosity decreases. The effects of pressing temperature and pressing time on the brazing performance of the composite solder sheets are significant

as high temperatures or prolonged pressing times can lead to increased oxidation of the tin powder and reduced flux activity

thereby decreasing brazing performance and increasing the rate of post-welding porosity. The effects of different process parameters on brazing expansion rate and cavity rate are relatively small. Composite solder sheets prepared under the conditions of 5

000 MPa pressure

30 s pressing time

and 60 ℃ temperature exhibit good brazing performance

with a minimum porosity of 7.2% and certain self-strength. These sheets demonstrate good wettability on nickel sheets and a post-welding cavity rate of less than 0.1%. Compared with traditional pre-formed solder sheets with surface-applied flux

the powder-pressed composite solder sheets have equivalent brazing performance and higher yield

making them technically feasible for batch application.