Lead-free Solder Sn-zn-xla Preparation And Study

Because of the lead and lead contained compounds' toxicity to human body and the environment. Many countrys which are including America,Japan and EU,etc have legislate to forbid lead used in microelectrical industry. So solders without lead have become the tendency of the electronic packaging's correlated welding.At present, most of the lead-free solders are Sn-based binary or ternary alloys with adding non-toxic and non-volatile elements, such as Ag,Zn, Cu, Bi and so on. It's proved that Sn-Ag ,Sn-Cu and Sn-Zn have the most outstanding characteristicand the most optimistic foreground in the mass.Here Sn-Zn was chosen as research object because of its good performance and low cost. Sn-9Zn alloy added different La contents (0. 1%～0. 5%) were prepared by powder metallurgy. The melting characteristic , microstructure and wettability ,shear strength on Cu substrate and forming and growing of IMC were researched carefully via analysis of SEM,XRD,DTA,etc.It was found that powder metallurgy is feasible process as a means to prepare lead-free solder especially in Lab which is simple and convenient ,low lost and can restrain solder to oxidate. Additional La would improve many characteristic,such as refining microstructure,better melting speciality and wettability.In the other hand,it will decrease shear strength appreciably.And we found that Sn-Zn-0.3La will be the best one in the series of Sn-Zn-xLa because of better perfomance,and it has considerable foreground to apply.