STUDY OF APPLICATION AND RELIABILITY OF LOW MELTING POINT Sn-Zn-Bi-In-P SYSTEM LEAD-FREE ALLOYS

摘要

The new Sn-Zn-Bi-In-P lead-free solder has goodrnsolderability, low melting point and the same reflowrnprofile as the Sn-37Pb eutectic solder. The bondingrnstrength of the Sn-Zn-Bi-In-P solder joint is 1.5 timesrnhigher than that of the Sn-37Pb solder joint. Afterrnthermal fatigue, the fatigue life of the former is 25%rnmore than that of the latter. The microstructure andrncomposition of the solder joint interface are also studied.rnA Zn-rich layer is found at the interface which canrnprevent the diffusion of Sn and Cu atoms, consequentlyrndecrease the thickness of the intermetallic compoundrnlayer. The results of EDX and TEM indicate that thernintermetallic compound is Cu5Zn8. The solder paste hasrnbeen produced and tested on the production line tornevaluate its performance.