Creep behavior of a lead-free solder alloy and construction of a validated Deformation Mechanism Map

随着对环境污染物的持续关注，铅在电子工业中成为目标，近年来一直在大力推动无铅化。2002年，欧洲联盟颁布了限制或消除大多数电气和电子设备中铅的使用的立法，随后日本和美国也颁布了立法。无铅焊料的引入意味着需要更新新的标准，因此需要有关特性和性能的新数据。该提案的合作伙伴公司Cistel正在努力获得有关航空电子应用中印刷电路板（PCB）所用无铅焊料的特性和性能的更好信息。PCB的主要问题是它们的失效，这与热疲劳有关，其中热冲击和热循环可以在PCB制造或使用期间发生。焊点的蠕变是恒定载荷下随时间变化的变形，其疲劳效应被认为是理解焊点热疲劳的基础，从而预测PCB寿命。随着新的无铅材料进入电子竞技场，需要更多的数据来了解这些合金中的蠕变机制。主要的无铅焊料被称为“SAC”，来自Sn-Ag-Cu三元合金。本文研究了一种Sn-Ag-Cu无铅钎料合金的蠕变行为。

With ongoing concerns regarding environmental pollutants, lead is being targeted in the electronic industry and there has been a strong push in recent years to go lead-free. In 2002 the European Union enacted legislations that restrict or eliminate the use of lead in most electrical and electronic equipment later followed by Japan and the United States. The introduction of lead-free solders means that new standards will need to be updated and thus new data on properties and performance will be required. The partner company in this proposal, Cistel, is working on obtaining better information on properties and performance of lead-free solder material used in printed circuit boards (PCB) for applications in avionics. The main issues with PCB is their failure which is related to thermal fatigue where thermal shock and thermal cycling can take place either during PCB manufacture or in service. Creep of solder joints, which is a time-dependent deformation under a constant load, and its effect of fatigue was recognized to be fundamental to understand thermal fatigue of soldered joints and thus to predict PCB lifetime. With new lead-free material coming in the electronic arena, more data is required to understand the creep mechanisms at play in these alloys. The predominant lead free solder is known as "SAC" from the ternary alloy of Sn-Ag-Cu. In this study the creep behavior of one formulation of Sn-Ag-Cu lead free solder alloy is investigated.