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以Sn-3.8Ag-0.7Cu钎料为对象,研究熔体结构转变和稀土元素Ce的添加对钎料性能的影响。研究发现Sn-3.8Ag-0.7Cu-xCe存在温度诱导的液-液结构转变,且经过熔体过热处理的钎料凝固组织较为细化,组织分布更加均匀,钎料的润湿性能和接头的剪切强度也得到提高;同时熔体结构转变还能够改善焊后界面IMC的形态。Ce的添加对钎料凝固组织有一定的影响,当Ce的质量分数大于0.2%时,随着Ce含量的增加,组织逐渐变得粗大、不均匀;另外,随着Ce含量的增加,钎料的润湿性能和接头剪切强度均呈先增加后降低的趋势,在试验范围内,当Ce的质量分数为0.2%时,钎料的润湿性能最佳,接头剪切强度最高。熔体结构转变和微量的Ce的添加均可以改善Sn-3.8Ag-0.7Cu钎料的性能。
Sn-3.8Ag-0.7Cu solder was taken as the object to study the effect of melt structure transformation and addition of rare-earth element Ce on the properties of brazing filler metal. The results show that there is temperature-induced liquid-liquid structure transition in Sn-3.8Ag-0.7Cu-xCe, and the solidified microstructure of the brazing filler metal after overheating is more refined and the distribution of the microstructure is more uniform. The solder wettability and the Shear strength is also improved; at the same time, melt structure transformation can also improve the shape of IMC after welding. The addition of Ce has a certain influence on the solidification structure of the brazing filler metal. When the mass fraction of Ce is more than 0.2%, the microstructure becomes coarse and inhomogeneous with the increase of Ce content. In addition, with the increase of Ce content, The wetting properties and the shear strength of the joints all increase first and then decrease. Within the experimental range, when the mass fraction of Ce is 0.2%, the wettability of the brazing filler metal is the best and the joint shear strength is the highest. The structure of Sn-3.8Ag-0.7Cu solder can be improved by changing the melt structure and adding a small amount of Ce.