Papers by Author: Li Juan Han

Abstract: The morphology and growing behavior of Cu₆Sn₅ intermetallic compound (IMC) of low Ag content Sn-2.5Ag-0.7Cu-0.1RE/Cu solder joint interface are investigated by adopting the X-ray diffraction, JSM-5610LV scanning electronic microscope and energy spectrum analysis. The results show that the cross-section morphology Cu₆Sn₅ of the solder joint interface is scallop-like and its section morphology is circle-like grain. With the aging time increasing, the cross-section Cu₆Sn₅ morphology of the solder joint interface can be changed from the scallop-like to the shape-layer, and the growing kinetics is coincidence with the law of parabola and its growing behavior is controlled by diffusion. With adding a small amount of rare earth elements in the Sn-2.5Ag-0.7Cu solder alloy, the growing rate of the Cu₆Sn₅ can be reduced.

Abstract: The interfacial microstructures and kinetics of low Ag content Sn2.5Ag0.7Cu/Cu solder joint were investigated by the X-ray diffraction, scanning electronic microscope and energy spectrum analysis during the isothermal aging. The results show that the interfacial microstructures of the Sn2.5Ag0.7Cu/Cu solder joint are composed of Cu₃Sn and Cu₆Sn₅ after soldering. With the aging time increasing, the intermetallic compound (IMC) pattern of the solder joint interface can be changed from the scallop-like to the shape-layer, and the growing dynamics is coincidence with the law of parabola and its growing behavior is controlled by diffusion. The growing activation energies values of Cu₃Sn and Cu₆Sn₅ layer at the Sn2.5Ag0.7Cu/Cu solder joint are 82.4kJ/mol and 69.6kJ/mol respectively.

Abstract: Effect of rare earth content on microstructure and interfacial reactions of low Ag content SnAgCu solder is researched by adopting the X-ray diffraction, JSM-5610LV scanning electronic microscope, energy spectrum analysis and JEM2100 ultrahigh resolution electron microscopy. The results show that proper quantities of rare earth (0.1%) can refine the eutectic microstructure of the solder alloy; and petal-like rare earth compound can be found in the solder alloy while the rare earth addition is 0.5%. The growing rate of the interfacial intermetallic compound can be reduced during the soldering with adding 0.1% rare earth in the Sn2.5Ag0.7Cu solder alloy.