Mechanism on formation of abnormally fine intermetallic compound grains in soldering reactions with eutectic lead-free solders
Abstract
This study demonstrates the mechanism governing interfacial intermetallic compound (IMC) grain refinement in eutectic solder systems during the initial stage of soldering reactions. The average IMC grain diameter generally increases with higher Cu or Ag contents in the solders, aligning with predictions from the concentration gradient controlled model, except for eutectic solders. The interfacial Cu6Sn5 and Ag3Sn grains in eutectic solder joints were significantly finer than those in non-eutectic solder joints, even 31% and 21% reductions compared to those in pure Sn solder joints after soldering for 60 s, respectively. Thermodynamic analysis reveals a critical phenomenon: the nucleation driving force (ΔGv∗) peaks at eutectic compositions (216.5 J/mol for Sn-0.7Cu and 239.3 J/mol for Sn–3.5Ag), which directly correlates with higher nucleation kinetics and final finer IMC grains. This mechanistic understanding provides crucial insights into nucleation-dominated microstructure control for advanced soldering technology.
Article Details
Journal Info
Journal of Applied Physics
American Institute of Physics
Authors (4)
S. B. Wang
Electronic Packaging Materials Laboratory, School of Materials Science and Engineering, Dalian University of Technology , Dalian 116024,
J. Ren
Electronic Packaging Materials Laboratory, School of Materials Science and Engineering, Dalian University of Technology , Dalian 116024,
B. Q. Zhang
Electronic Packaging Materials Laboratory, School of Materials Science and Engineering, Dalian University of Technology , Dalian 116024,
M. L. Huang
Electronic Packaging Materials Laboratory, School of Materials Science and Engineering, Dalian University of Technology , Dalian 116024,