Microstructural development in a rapidly cooled eutectic Sn–3.5% Ag solder reinforced with copper powder
Microstructural development in a rapidly cooled eutectic Sn–3.5% Ag solder reinforced with copper powder
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DOI：
10.1016/j.powtec.2006.02.009
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发表时间：
2006-08
影响因子：
5.2
通讯作者：
D. Lin;T. Srivatsan;Guo-xiang Wang;R. Kovacevic
中科院分区：
文献类型：
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作者：
D. Lin;T. Srivatsan;Guo-xiang Wang;R. Kovacevic
使用共晶Sn-3.5%Ag焊膏进行实验，目的是检查铜颗粒添加和快速冷却对显微组织发展的联合影响。复合焊料混合物通过将预先称重的量的铜颗粒与商业Sn-3.5%Ag焊料膏充分混合来制备。实验与工业回流焊接工艺的加热和冷却循环非常相似。样品的加热在温度被仔细控制的炉中进行。冷却过程在冷却的铝块上进行，冷却剂在0.5 °C下循环通过该铝块。当焊料温度达到250 °C时，循环系统将自动打开，并且仍处于熔融状态的样品将被迫快速冷却。焊料样品的温度记录显示，与未增强的Sn-3.5%Ag对应物相比，向共晶Sn-3.5%Ag中添加铜颗粒不会明显影响加热和熔化性能。然而，铜颗粒确实改变了复合焊料的凝固温度。对不同量的铜颗粒添加的详细观察显示，小于1.0重量%的铜颗粒添加量为0.001重量%。降低了复合钎料的凝固温度。对于大于1.0重量%的铜颗粒，固化温度升高了几摄氏度，表明在熔化过程中，一些铜颗粒没有完全溶解在Sn占优势的焊料中。结果表明，Sn-3.5%Ag共晶钎料的凝固组织中含有富Sn相的柱状枝晶和位于枝晶柱之间的Sn 3Ag和富Sn相的共晶混合物。Cu颗粒的加入细化了共晶Sn-3.5%Ag钎料的初生相的形貌，这是由于Cu_6Sn_5金属间化合物在钎料基体中的存在和分布。
Experiments using eutectic Sn–3.5% Ag solder paste were conducted with the objective of examining the conjoint influence of copper particles addition and rapid cooling on microstructural development. The composite solder mixture was made by thoroughly mixing a pre-weighed amount of copper particles with a commercial Sn–3.5% Ag solder paste. The experiments were quite similar to the heating and cooling cycle of an industrial reflow soldering process. Heating of the samples was conducted in a furnace whose temperature was carefully controlled. The cooling process was conducted on a chilled aluminum block through which coolant was circulated at 0.5 °C. When the solder temperature reached 250 °C, the circulating system would turn on automatically and the sample, which is still molten, is forced to cool rapidly. Temperature records of the solder samples revealed that addition of copper particles to the eutectic Sn–3.5% Ag did not appreciably affect the heating and melting properties when compared to the unreinforced Sn–3.5% Ag counterpart. However, copper particles did change the solidification temperature of the composite solder. Detailed observations for varying amounts of copper particle addition revealed that copper particles less than 1.0 wt.% lowered the solidification temperature of the composite solder. For copper particles greater than 1.0 wt.%, the solidification temperature increased a few degrees Celsius, indicating that some of the copper particles did not completely dissolve in the Sn-dominant solder during the melting process. Results reveal that as-solidified microstructures of the eutectic Sn–3.5% Ag solder contain columnar type dendrites of the Sn-rich phase and a eutectic mixture of the Sn3Ag and Sn-rich phase located between the dendrite columns. The addition of copper particles to the eutectic Sn–3.5% Ag solder does refine the morphology of the primary phase, which is attributed to the presence and distribution of the Cu6Sn5intermetallic in the solder matrix.