Abstract: The influence of Sn concentration on processability and solderability of Ag-Cu-In alloys were investigated. The result shows that Sn addition in Ag-Cu-In alloys can effectively reduced the melting temperature of the solder. When the alloy with 8% Sn concentration, the melting temperature is 575～620 ℃, the composite solder can be processed into strip, the trip with thickness of 0.1 mm,and the composite solder has good welding performance. However with Sn concentration increasing, when the Sn concentration is more than 8%, excessive Sn addition promotes formation of the coarse second phase particles, which results in the deterioration of processability.