Fatigue of Advanced In-Situ Composite Solders

摘要

Solder Joints used in surface mount technology experience thermomechanicalfatigue due to the mismatches in coefficients of thermal expansion of the electrical component, the printed circuit board, and the solder itself, which during thermal cycles causes the solder Joint to undergo shear strains. The purpose of this study was to examine and explain the thermomechanical fatigue damage mechanisms of various types of solder compositions. Shear, creep, low cycle fatigue, and thermomechanical fatigue tests were conducted in this research. The development of cracks through heterogeneously coarsened, Sn-enriched bands was observed in Sn-Pb eutectic and solid solution strengthened alloys failed in thermomechanical fatigue. The dominant damage mechanism for these alloys was determined to be dislocation climb. Dispersion strengthening inhibited heterogeneous coarsening, and resulted in solders with greater thermomechanical fatigue lifetimes.