快速凝固对Sn-8Zn-3Bi合金特性及高温时效钎料/铜焊点结构演变的影响

摘要

研究了快速凝固工艺对Sn?8Zn?3Bi合金显微组织和熔化特性的影响，分析了经150°C高温时效后钎料/铜焊点显微组织演变以评估连接的可靠性。结果表明：经快速凝固后，Sn?8Zn?3Bi 合金中的 Bi 完全固溶于Sn基体并形成枝晶结构；与常规熔铸态合金相比，Bi在Sn基体中的过饱和固溶导致快速凝固态钎料的熔点上升至接近Sn?Zn共晶合金熔点，但同时减小了由于Bi添加对Sn?Zn合金熔化行为产生的不利影响，钎料/铜焊点界面金属间化合物(IMC)层更为致密和均匀；使用快速凝固态钎料能够显著抑制高温时效过程中钎料/铜焊点界面IMC的形成与生长并改善其界面高温稳定性。%The effects of rapid solidification on the microstructure and melting behavior of the Sn?8Zn?3Bi alloy were studied. The evolution of the microstructural characteristics of the solder/Cu joint after an isothermal aging at 150 °C was also analyzedto evaluate the interconnect reliability. Results showed that the Bi in Sn?8Zn?3Bi solder alloy completely dissolved in the Sn matrix with a dendritic structure after rapid solidification. Compared with as-solidified Sn?8Zn?3Bi solder alloy, the melting temperature of the rapid solidified alloy rose to close to that of the Sn?Zn eutectic alloy due tothe extreme dissolution of Bi in Sn matrix. Meanwhile, the adverse effect on melting behavior due to Bi addition wasdecreasedsignificantly. The interfacial intermetallic compound (IMC) layer of the solder/Cu joint was more compact and uniform. Rapid solidification process obviously depressed the formation and growth of the interfacial IMC during the high-temperature aging and improved the high-temperature stability of the Sn?8Zn?3Bi solder/Cu joint.