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本文研究了Sn-0.7Cu-Bi系无铅钎料微观组织、润湿性能及接头剪切强度,进而研究Bi元素对Sn-0.7Cu无铅钎料的影响规律。结果表明:Sn-0.7Cu-Bi系无铅钎料显微组织由β-Sn相、富Cu相及Bi的析出物组成,随Bi质量分数的增加,β-Sn晶粒得到细化;添加适量的Bi可显著提高钎料的润湿性能和接头剪切强度,但Bi质量分数超过5%时,接头剪切强度随Bi的增加而降低。
In this paper, the microstructure, wettability and joint shear strength of Sn-0.7Cu-Bi lead-free solder were studied, and then the influence of Bi on Sn-0.7Cu lead-free solder was studied. The results show that the microstructure of Sn-0.7Cu-Bi lead-free solder consists of β-Sn phase, Cu-rich phase and Bi precipitates. The β-Sn crystal grains are refined with the increase of Bi mass fraction. Appropriate amount of Bi can significantly improve the wetting properties of solder and joint shear strength, but when the Bi mass fraction exceeds 5%, the joint shear strength decreases with the increase of Bi.