等温时效对新型Sn-Ag基复合钎料显微组织和力学性能的影响

研究了等温时效对Sn-3.5Ag共晶钎料及其复合钎料的力学性能和显微组织变化的影响。为了弥补传统复合钎料制备和服役中强化颗粒容易粗化的问题， 制备了不同种类最佳配比的具有纳米结构的有机无机笼型硅氧烷齐聚物(POSS)颗粒增强的Sn-Ag基复合钎料。对钎焊接头在不同温度（125、150、175℃）下进行时效，通过SEM和EDAX分析了钎料与基板间金属间化合物层(IMC)的生长情况。结果表明， 经过不同温度时效，复合钎料钎焊接头界面处金属间化合物的生长速率比Sn3.5Ag共晶钎料慢， 复合钎料的IMC生长的激活能分别为80、97和77kJ/mol，均高于Sn3.5Ag共晶钎料。经过150℃时效1000h后，复合钎料钎焊接头的剪切强度分别下降了22%、13%和18%，下降幅度相当或明显小于Sn-3.5Ag钎料钎焊接头。 

Microstructure evolution and mechanical properties of Sn-Ag based composite solder joints during isothermal aging

The microstructure evolution and mechanical properties of Sn-3.5Ag and its new composite solder containing three different nano-sized polyhedral oligomeric silsesquioxanes (POSS) particulates with the best mass fractions during isothermal aging were studied. All of the above four solder joints were aged at three different temperatures (125℃，150℃，175℃) up to 1000 h and the intermetallic compound growth was measured. The interfacial layers between the solder and the copper substrate were examined using the optical and scanning electronic microscopy. The growth kinetics of intermetallic interfacial layers formed between the solder and the copper substrate was characterized. The growth rate of the intermetallic layers of the composite solders is slower than that of Sn-3.5Ag solder. The activation energies of the composite solders are 80，97 and 77kJ/mol, respectively，and are higher than those of Sn-3.5Ag solder. Besides，the shear strength of the composite solder joints is higher and not so sensitive to the different aging processes.