快速凝固Sn-3.5Ag-0.7Cu钎料特性及钎焊界面反应研究

发布时间：2018-05-15 11:48

  本文选题：快速凝固Sn-3.5Ag-0.7Cu + 激光钎焊　； 参考：《大连理工大学》2015年硕士论文

【摘要】：传统Sn-Pb钎料具有毒性,严重威胁着环境质量和人体健康,因此,研究开发新的、高性能无铅钎料势在必行。Sn-Ag-Cu系钎料合金以其较好的综合性能成为Sn-Pb钎料的最佳替代品,然而,其熔点仍相对较高。因此,利用快速凝固技术改善其性能,并对其做进一步研究分析意义重大。本文以单辊甩带法制备的快速凝固Sn-3.5Ag-0.7Cu钎料为研究对象,系统研究分析了其微观组织、熔化特性及不同钎焊时间下界面金属间化合物(IMC)的生长行为；同时利用激光钎焊快速凝固Sn-3.5Ag-0.7Cu/Cu接头,探求合适的激光工艺参数：最后对比分析了快速凝固和普通凝固Sn-3.5Ag-0.7Cu/Cu接头的剪切强度和断口形貌。旨在为快速凝固无铅钎料在电子封装领域的广泛使用提供理论参考。获得的主要结论如下：(1)与普通凝固Sn-3.5Ag-0.7Cu钎料相比,快速凝固Sn-3.5Ag-0.7Cu钎料合金的组织更均匀、熔点更低、熔化速度更快。(2)250℃下,短时钎焊时,快速凝固Sn-3.5Ag-0.7Cu/Cu界面Cu6Sn5晶粒尺寸比普通凝固Sn-3.5Ag-0.7Cu/Cu界面处的大,并且随钎焊时间延长晶粒形貌从小面状转变成扇贝状,而普通凝固Sn-3.5Ag-0.7Cu/Cu界面Cu6Sns晶粒却在钎焊15s时才出现面状；长时间回流焊接时,快速凝固Sn-3.5Ag-0.7Cu/Cu界面IMC厚度比普通凝固界面处的厚；快速凝固Sn-3.5Ag-0.7Cu钎料适合于低温、短时钎焊。(3)激光功率一定时,随扫描速度降低,快速凝固Sn-3.5Ag-0.7Cu/Cu界面Cu6Sn5晶粒形貌先出现均匀、细小的扇贝状,再从扇贝状转变成棱柱状,并且随着扫描速度降低棱柱状Cu6Sn5晶粒尺寸增大；再次减小扫描速度时,观察到底部排列紧密,顶部有凸起的晶粒；扫描速度再次降低时,界面及钎料内部形成大板块状Cu6Sn5晶粒。(4)在激光功率50 w,扫描速度140 mm/min钎焊时,快速凝固和普通凝固Sn-3.5Ag-0.7Cu/Cu界面IMC均呈细小扇贝状,但前者晶粒尺寸稍大；时效时,IMC尺寸随时效时间延长而变大,但普通凝固Sn-3.5Ag-0.7Cu/Cu界面IMC尺寸更大。(5)在250℃,钎焊20s、30s和50s时,快速凝固Sn-3.5Ag-0.7Cu/Cu钎焊接头剪切强度比普通凝固Sn-3.5Ag-0.7Cu/Cu钎焊接头的大；而80 s时,则相反；前者的剪切强度随着钎焊时间增加而增加,而后者的剪切强度却随钎焊保温时间先增加后减小。
[Abstract]:The traditional Sn-Pb solder is toxic, which is a serious threat to environmental quality and human health. Therefore, it is imperative to develop new and high performance lead-free filler metal Sn-Ag-Cu series brazing alloy as the best substitute for Sn-Pb solder with its better comprehensive properties. The melting point is still relatively high. Therefore, it is of great significance to use rapid solidification technology to improve its performance and to further study and analyze it. In this paper, the microstructure, melting characteristics and the growth behavior of intermetallic intermetallics at different brazing time were studied systematically with the rapid solidification Sn-3.5Ag-0.7Cu solder prepared by single roll strip throwing method. At the same time, the laser brazing of rapidly solidified Sn-3.5Ag-0.7Cu/Cu joints was used to find out the appropriate laser parameters. Finally, the shear strength and fracture morphology of rapidly solidified and ordinary solidified Sn-3.5Ag-0.7Cu/Cu joints were compared and analyzed. The aim is to provide a theoretical reference for the wide application of rapidly solidified lead-free solders in electronic packaging. The main conclusions obtained are as follows: compared with ordinary solidified Sn-3.5Ag-0.7Cu solder, the microstructure of rapidly solidified Sn-3.5Ag-0.7Cu brazing alloy is more uniform, the melting point is lower, and the melting rate is faster. The grain size of Cu6Sn5 at the rapidly solidified Sn-3.5Ag-0.7Cu/Cu interface is larger than that at the common solidified Sn-3.5Ag-0.7Cu/Cu interface, and with the prolonging of the brazing time, the morphology of the Cu6Sn5 grain changes from small to scalloped, while the Cu6Sns grain of the common solidified Sn-3.5Ag-0.7Cu/Cu interface appears only after 15 seconds of brazing. For long time reflux welding, the IMC thickness of rapidly solidified Sn-3.5Ag-0.7Cu/Cu interface is thicker than that of ordinary solidification interface, and the rapid solidified Sn-3.5Ag-0.7Cu solder is suitable for low temperature, short time brazing. The morphology of Cu6Sn5 grains at the rapid solidification Sn-3.5Ag-0.7Cu/Cu interface first appears uniform, fine scallop shape, then changes from scallop shape to prism shape, and increases with the decrease of scanning speed, and decreases the scanning speed again. It is observed that the bottom is tightly arranged and the top has bulge grains, and when the scanning speed decreases again, the large plate-like Cu6Sn5 grains. 4) are formed in the interface and inside of the solder. When the laser power is 50 ws, the scanning speed is 140 mm/min. The IMC of Sn-3.5Ag-0.7Cu/Cu interface of rapid solidification and ordinary solidification are both fine scallop, but the grain size of the former is slightly larger, and the size of Sn-3.5Ag-0.7Cu/Cu increases with the time of aging, but the size of IMC at the interface of ordinary solidification Sn-3.5Ag-0.7Cu/Cu is larger than that of normal solidified Sn-3.5Ag-0.7Cu/Cu at 250 鈩，

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