Abstract: The effects of Ag content on the melting temperature, wettability and mechanical properties of the soldered joints were investigated.Microstructures and shear strength of SnAgCuX soldered joint were also studied under both as-reflowed and after high temperature aging conditions.X includes Ni, P and Ce element.The experimental results indicate that the addition of trace amounts X element can remedy the decrease in properties of the solders to a certain extent due to the decrease of Ag content.Adding trace amounts of X element has little influence on the melting temperature of the solders, but obviously improves the wettability of solder and the shear strength of the soldered joints, and markedly decreases the effect of high-temperature aging on shear strength.The reason may be related to the modification of the microstructure and IMC of the solder alloys due to the addition of trace amounts of X elements.