Instability of the Wetting Tip in Lead-Free Solder Reactions

小行星9705195 本研究旨在探讨无铅焊锡对薄膜金属化之润湿行为。 重点是在焊接过程中的润湿尖端行为和金属间化合物的形成。 研究的是一种独特的薄膜反应，其中晶粒成熟和剥落导致去湿。 为了理解反应润湿的基础科学和在电子封装中的薄膜金属化的应用，两个主要的主题是研究的焦点：（1）反应润湿尖端的不稳定性和（2）剥落和去湿的机制。研究了稀铅（锡）合金中锡的组成对润湿角的影响。 预期在Pb（Sn）在Ni上的情况下观察到的润湿角变化将小于Pb（Sn）在Cu上的润湿角变化，而Cu上的润湿角变化又将远小于Pb（Sn）在Pd上的润湿角变化。 以往的工作表明，熔融共晶SnPb在Pd上的润湿角是不稳定的，并随时间而变化。 对Ni、Cu和Pd表面进行了系统的比较研究。 %焊接技术是电子封装的关键。 半导体工业协会（SIA）已经预测了在器件制造中增加使用焊料的趋势。 然而，美国国会和环境规划署（EPA）对电子工业中铅的使用表示关注。 因此，需要研究无铅焊料及其工艺、性能和可靠性。 ***

9705195 Tu It is the purpose of this research to investigate the wetting behavior of Pb-free solders on thin film metallization. Emphasis is on the wetting tip behavior and intermetallic compound formation during soldering. Investigated is a unique thin film reaction where the grains ripen and spall resulting in dewetting. To understand the basic science of reactive wetting and the applications to thin film metallization in electronic packaging, two main topics are the focus of the research: (1) the instability of a reactive wetting tip and (2) the mechanisms of spalling and dewetting. The dependence of wetting angle on the composition of Sn in dilute Pb(Sn) alloys is examined. It is expected that the wetting angle changes observed in the case of Pb(Sn) on Ni will be less than that of Pb(Sn) on Cu, which, in turn, will be much less than that of Pb(Sn) on Pd. Previous work shows that the wetting angle of molten eutectic SnPb on Pd is unstable and changes with time. A systematic and comparative study on Ni, Cu, and Pd surfaces is conducted.. %%% Solder technology is essential for electronic packaging. The Semiconductor Industry Association (SIA) has projected a trend of increasing use of solder in device manufacturing. The US Congress and Environmental Projection Agency (EPA), however, has expressed a concern over the use of Pb in the electronics industry. As a consequence, lead (Pb)-free solders and their processes, properties and reliability need to be studied. ***