Tin-Silver-Copper is widely accepted as the best alternative to replace Tin-Lead solders in microelectronics packaging due to their acceptable properties. However, to overcome some of the shortcomings related to its microstructure and in turn, its mechanical properties at high temperature, the addition of different elements into Tin-Silver-Copper is important for investigations. The purpose of this paper is to analyse the effect of lanthanum doping on the microstructure, microhardness and tensile properties of Tin-Silver-Copper as a function of thermal aging time for 60, 120 and 180 h at a high temperature of 150°C and at high strain rates of 25, 35 and 45/s.,The microstructure of un-doped and Lanthanum-doped Tin-Silver-Copper after different thermal aging time is examined using scanning electron microscopy followed by digital image analyses using ImageJ. Brinell hardness is used to find out the microhardness properties. The tensile tests are performed using the universal testing machine. All the investigations are done after the above selected thermal aging time at high temperature. The tensile tests of the thermally aged specimens are further investigated at high strain rates of 25, 35 and 45/s.,According to the microstructural examination, Tin-Silver-Copper with 0.4 Wt.% Lanthanum is found to be more sensitive at high temperature as the aging time increases which resulted in coarse microstructure due to the non-uniform distribution of intermetallic compounds. Similarly, lower values of microhardness, yield strength and ultimate tensile strength come in favours of 0.4 Wt.% Lanthanum added Tin-Silver-Copper. Furthermore, when the thermally aged tensile specimen is tested at high strains, two trends in tensile curves of both the solder alloys are noted. The trends showed that yield strength and ultimate tensile strength increase as the strain rate increase and decrease when there is an increase in thermal aging.,The addition of higher supplement (0.4 Wt.%) of Lanthanum into Tin-Silver-Copper showed a lower hardness value, yield strength, ultimate tensile strength, ductility, toughness and fatigue in comparison to un-doped Tin-Silver-Copper at high temperature and at high strain rates. Finally, simplified material property models with minimum error are developed which will help when the actual test data are not available.

中文翻译：

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SAC305和SAC305-0.4La无铅电子焊锡高温性能

锡银铜因其可接受的特性而被广泛接受为微电子封装中替代锡铅焊料的最佳替代品。然而，为了克服与其微观结构相关的一些缺点，进而克服其高温机械性能，将不同元素添加到锡-银-铜中对于研究很重要。本文的目的是分析镧掺杂对锡-银-铜的显微组织、显微硬度和拉伸性能的影响，作为在 150°C 和 60、120 和 180 h 的高温下的热老化时间的函数，以及在 25、35 和 45/s 的高应变率下，使用扫描电子显微镜检查未掺杂和镧掺杂的锡-银-铜在不同热老化时间后的微观结构，然后使用 ImageJ 进行数字图像分析。布氏硬度用于确定显微硬度特性。使用万能试验机进行拉伸试验。所有的研究都是在上述选定的高温热老化时间后进行的。在 25、35 和 45/s 的高应变率下进一步研究了热老化试样的拉伸试验。根据微观结构检查，发现含有 0.4 Wt.% 镧的锡银铜在高应变率下更敏感。温度随着时效时间的增加，由于金属间化合物的不均匀分布，导致显微组织粗大。同样，较低的显微硬度值，屈服强度和极限抗拉强度有利于添加 0.4 Wt.% 镧的锡-银-铜。此外，当热老化拉伸试样在高应变下进行测试时，两种焊料合金的拉伸曲线都有两种趋势。趋势表明屈服强度和极限拉伸强度随着应变速率的增加而增加，而随着热老化的增加而减少。在锡-银-铜中添加较高的镧（0.4 Wt.%）显示出较低的与未掺杂的锡银铜在高温和高应变率下的硬度值、屈服强度、极限拉伸强度、延展性、韧性和疲劳相比。最后，开发了具有最小误差的简化材料属性模型，这将在实际测试数据不可用时提供帮助。