TY - GEN
T1 - Microstructural evolution of Sn-3.5Ag solder with lanthanum addition
AU - Lee, Hwa Teng
AU - Chen, Yin Fa
AU - Hong, Ting Fu
AU - Shih, Ku Ta
AU - Hsu, Che Wei
PY - 2009
Y1 - 2009
N2 - The goal of this research is to evaluate the effects of La addition on the microstructure and microhardness of Sn-Ag based solders. Sn-3.5Ag-xLa ternary alloy solders were prepared by adding 0-1.0wt% La into a Sn-3.5Ag alloy. Copper substrates were then dipped into these solders and aged at 150°C for up to 625 hours. The microstructure and microhardness of the as solidified solder and the aged solder/copper couples were investigated. Experimental results show that Sn-3.5Ag-xLa solders are composed of β-Sn, Ag3Sn, and LaSn 3 phases, and that their microstructure is refined with La addition. After isothermal storage, the Ag3Sn and IMC layer can be effectively depressed by adding a small amount of La element, and the size and amount of LaSn3 compounds does not change perceptibly with storage time. For as-cast solder, the addition of La increased the microhardness of the Sn-Ag solder due to the refining effect of Ag3Sn particles in the eutectic zone and increased formation of LaSn3 compound. After isothermal storage, the microhardness of solders was decreased with the increasing coarsening of Ag3Sn compounds as aging time was increased. However, coarsening of Ag3Sn compounds was retarded by La addition. Therefore, La addition helped to improve the microhardness and thermal resistance of the solder joints.
AB - The goal of this research is to evaluate the effects of La addition on the microstructure and microhardness of Sn-Ag based solders. Sn-3.5Ag-xLa ternary alloy solders were prepared by adding 0-1.0wt% La into a Sn-3.5Ag alloy. Copper substrates were then dipped into these solders and aged at 150°C for up to 625 hours. The microstructure and microhardness of the as solidified solder and the aged solder/copper couples were investigated. Experimental results show that Sn-3.5Ag-xLa solders are composed of β-Sn, Ag3Sn, and LaSn 3 phases, and that their microstructure is refined with La addition. After isothermal storage, the Ag3Sn and IMC layer can be effectively depressed by adding a small amount of La element, and the size and amount of LaSn3 compounds does not change perceptibly with storage time. For as-cast solder, the addition of La increased the microhardness of the Sn-Ag solder due to the refining effect of Ag3Sn particles in the eutectic zone and increased formation of LaSn3 compound. After isothermal storage, the microhardness of solders was decreased with the increasing coarsening of Ag3Sn compounds as aging time was increased. However, coarsening of Ag3Sn compounds was retarded by La addition. Therefore, La addition helped to improve the microhardness and thermal resistance of the solder joints.
UR - http://www.scopus.com/inward/record.url?scp=70450008673&partnerID=8YFLogxK
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U2 - 10.1109/ICEPT.2009.5270676
DO - 10.1109/ICEPT.2009.5270676
M3 - Conference contribution
AN - SCOPUS:70450008673
SN - 9781424446599
T3 - 2009 International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2009
SP - 617
EP - 622
BT - 2009 International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2009
T2 - 2009 International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2009
Y2 - 10 August 2009 through 13 August 2009
ER -