Effects of rare earth element Ce on solderabilities of micron-powdered Sn-Ag-Cu solder

Several important properties of the micron-powdered Sn-Ag-Cu-Ce solder, including the spreadability, spreading ratio, wetting time, and melting point, were investigated for verifying the effects of rare earth element Ce on solderabilities of micron-powdered Sn-Ag-Cu solder. The solidus and the liquidus of the micron-powdered Sn-Ag-Cu-Ce solder are 193.6 degrees C and 218.4 degrees C, respectively, about 28 degrees C and 3 degrees C lower than the melting point of the block Sn-Ag-Cu solder, which reminds the existence of the surface effect of the micron-powdered solder. By adding Ce into Sn-Ag-Cu alloy, its wetting time on pure copper can be obviously decreased. For the Sn-Ag-Cu-0.03%Ce, the soldering temperature is 250 degrees C, and the wetting time on pure copper is close to 1 s, with the soldering temperature approaching to 260 the wetting time is dropped to 0.8 s, which is close to the wetting time, 0.68 s, of Sn-Pb solder at 235 degrees C.