Leong Yee Mei, Haseeb A S M A
Centre for Advanced Materials, Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia.
Materials (Basel). 2016 Jun 28;9(7):522. doi: 10.3390/ma9070522.
Driven by the trends towards miniaturization in lead free electronic products, researchers are putting immense efforts to improve the properties and reliabilities of Sn based solders. Recently, much interest has been shown on low silver (Ag) content solder SAC105 (Sn-1.0Ag-0.5Cu) because of economic reasons and improvement of impact resistance as compared to SAC305 (Sn-3.0Ag-0.5Cu. The present work investigates the effect of minor aluminum (Al) addition (0.1-0.5 wt.%) to SAC105 on the interfacial structure between solder and copper substrate during reflow. The addition of minor Al promoted formation of small, equiaxed Cu-Al particle, which are identified as Cu₃Al₂. Cu₃Al₂ resided at the near surface/edges of the solder and exhibited higher hardness and modulus. Results show that the minor addition of Al does not alter the morphology of the interfacial intermetallic compounds, but they substantially suppress the growth of the interfacial Cu₆Sn₅ intermetallic compound (IMC) after reflow. During isothermal aging, minor alloying Al has reduced the thickness of interfacial Cu₆Sn₅ IMC but has no significant effect on the thickness of Cu₃Sn. It is suggested that of atoms of Al exert their influence by hindering the flow of reacting species at the interface.
在无铅电子产品小型化趋势的推动下，研究人员正付出巨大努力来改善锡基焊料的性能和可靠性。最近，由于经济原因以及与SAC305（Sn-3.0Ag-0.5Cu）相比抗冲击性有所提高，低银（Ag）含量焊料SAC105（Sn-1.0Ag-0.5Cu）受到了广泛关注。本工作研究了向SAC105中添加微量铝（Al）（0.1-0.5 wt.%）对回流过程中焊料与铜基板之间界面结构的影响。微量Al的添加促进了细小等轴Cu-Al颗粒的形成，这些颗粒被鉴定为Cu₃Al₂。Cu₃Al₂位于焊料的近表面/边缘，表现出更高的硬度和模量。结果表明，微量Al的添加并未改变界面金属间化合物的形态，但它们在回流后显著抑制了界面Cu₆Sn₅金属间化合物（IMC）的生长。在等温时效过程中，微量合金化Al降低了界面Cu₆Sn₅ IMC的厚度，但对Cu₃Sn的厚度没有显著影响。据推测，Al原子通过阻碍界面处反应物种的流动来发挥其影响。
