Title :
High reliable solder joints using Sn-Pb-La solder alloy
Author :
Ma, X. ; Qian, Y.Y. ; Liu, F. ; Yoshida, F.
Author_Institution :
Nat. Key Lab. of Reliability Phys. of Electron. Product, Guangzhou, China
Abstract :
Reliability of solder joints is essential to electronic packaging since they provide both the mechanical and electrical connections at PCB level assembly. Several efforts have been made to improve the mechanical properties of traditional Sn60-Pb40 solder alloys by adding small amounts of alloy elements, such as Ag, Sb, Cu, Pd, etc. (Vaynman et al., 1998; Takemoto et al., 1997; Devore, 1982). Although the provided experimental data illustrated the effect of improvements, the corresponding modification mechanism had been little discussed. In this work, a small amount of rare earth element La was added to Sn60-Pb40 solder in order to improve the reliability of solder joints without increasing the melting point. High temperature tensile tests of solder alloys and thermal fatigue tests of solder joints were conducted to validate the improvement. SEM observation further clarified the corresponding microstructure modification. Finally, the effect of adding small amount of La was deeply studied based upon thermodynamic models and eutectic growth kinetics
Keywords :
assembling; circuit reliability; crystal microstructure; eutectic alloys; fatigue testing; lanthanum alloys; lead alloys; melting point; packaging; printed circuit testing; reaction kinetics; scanning electron microscopy; soldering; tensile testing; thermal stress cracking; tin alloys; Ag; Ag alloy element; Cu; Cu alloy element; PCB level assembly; Pd; Pd alloy element; SEM; Sb; Sb alloy element; Sn-Pb solder alloys; Sn-Pb-La solder alloy; SnPb; SnPbLa; electrical connections; electronic packaging; eutectic growth kinetics; high temperature tensile tests; mechanical connections; mechanical properties; melting point; microstructure modification; rare earth element La addition; reliability; reliable solder joints; solder alloys; solder joint reliability; solder joints; thermal fatigue tests; thermodynamic models; Aluminum alloys; Assembly; Copper alloys; Electronics packaging; Mechanical factors; Soldering; Temperature; Testing; Thermal conductivity; Tin alloys;
Conference_Titel :
Physical and Failure Analysis of Integrated Circuits, 2001. IPFA 2001. Proceedings of the 2001 8th International Symposium on the
Print_ISBN :
0-7803-6675-1
DOI :
10.1109/IPFA.2001.941456