Development of Lead-Free Solders with Superior Drop Test Reliability Performance
The objective of this study is to investigate the alloying effects of Fe, Co, and Ni on the interfacial reactions between solder and Cu. Emphasis is placed on a systematic comparison study on the effect of Fe, Co, and Ni additions. Solders with simultaneous Fe and Ni addition as well as simultaneous Co and Ni addition are also prepared in order to investigate whether there is any interaction between the alloying elements. The results of this study can be summarized as below: (1) In multiple reflow study using the Sn2.5Ag0.8Cu, Sn2.5Ag0.8Cu0.03Fe, Sn2.5Ag0.8Cu0.03Co, Sn2.5Ag0.8Cu0.03Ni, Sn2.5Ag0.8Cu0.03Fe0.03Ni, and Sn2.5Ag0.8Cu0.03Co0.03Ni solder over Cu substrate, Cu6Sn5 was the only reaction product for all the different solders used. (2) Reflows using the solder without doping produced a thin, dense layer of Cu6Sn5. The additions of Fe, Co, or Ni transformed the microstructure into a much thicker Cu6Sn5 with many small trapped solder regions between the grains. (3) The amount of Cu6Sn5 formed at the interface increased with the number of reflows. (4) In solid state aging study, both Cu6Sn5 and Cu3Sn formed, but the additions of Fe, Co, or Ni produced a much thinner Cu3Sn layer in all cases in this study. The growth of Cu3Sn followed the parabolic kinetics. (5) The simultaneous addition of 0.03 wt.％ of Fe and Ni was the most effective in reducing the Cu3Sn thickness. The Cu3Sn thickness was only one-third that of Sn2.5Ag0.8Cu. (6) The additions of Fe, Co, or Ni in an amount as small as 0.03 wt.％ were effective in reducing the Cu3Sn thickness at 160℃ for at least 2000 hrs.
Y. W. Wang C. R. Kao
Department of Materials Science & EngineeringTaiwan UniversityTaipei City, Taiwan, China
国际会议
北京
英文
534-539
2009-08-10（万方平台首次上网日期，不代表论文的发表时间）