稀土Y加速Sn晶须生长规律

Study of tin whisker growth accelerated by rare earth Y

摘要: 氧原子向稀土相YSn₃晶格内部的扩散使YSn₃产生体积膨胀,而周围钎料基体对体积膨胀的抑制作用使其内部产生巨大的压应力,此压应力为Sn晶须的生长提供了驱动力;与此同时,稀土相YSn₃氧化过程中释放出的自由Sn原子为Sn晶须的生长提供了生长源.对空气中室温与150℃时效条件下稀土相YSn₃表面Sn晶须的生长进行了研究.结果表明,室温时效条件下,稀土相YSn₃表面Sn晶须的生长速度缓慢且分布不均;高温时效条件下,稀土相YSn₃表面Sn晶须的生长速度较快且巨大的压应力使钎料基体发生了隆起现象。

Abstract: It is known that rare-earth elements exhibit high chemical activity and adding trace amount of rare-earth(RE) in the solder can significantly improve the properties of solder alloy.However, RE-phases with large size precipitated in the Sn-3.8Ag-0.7Cu-1.0 RE solder alloy are oxidized when exposed in air, tin whiskers growing rapidly on the surface of the oxidized RE-phases.Tin whisker growth on the surface of the oxidized YSn₃ phase is investigated at room temperature and 150℃ storage in air respectively.The results indicate that tin whiskers grow slowly and distribute unevenly on the surface of the oxidized YSn₃ phases during room temperature storage in air, but tin whiskers grow rapidly and the YSn₃ phase is extruded around even solder matrix during 150℃ storage in air.