Abnormal growth of Ag_(3)Sn intermetalUc compounds in Sn-Ag lead-free solder  

Abnormal growth of Ag_3Sn intermetallic compounds in Sn-Ag lead-free solder

作　　者：SHEN Jun LIU Yongchang GAO Houxiu 

机构地区：[1]College of Mechanical Engineering, Chongqing University, Chongqing 400044, China [2]College of Materials Science & Engineering, Tianjin University, Tianjin 300072, China

出　　处：《Chinese Science Bulletin》2006年第14期1766-1770,共5页

基　　金：supported by the National Natural Science Foundation of China(Grant No.50401033);the Liu Hui Applied Mathematics Center of Nankai University and Tianjin University(Grant No.T13).

摘　　要：The abnormal growth of Ag3Sn inter-metallic compounds in eutectic Sn-3.5% Ag solder was investigated through high-temperature aging treatment. Microstructural evolutions of this solder before and after the aging treatment were observed by optical microscopy and scanning electron mi-croscopy. Precise differential thermal analysis was made to study the changes in enthalpies of the solder under different conditions. The results reveal that the water-cooled solder is in metastable thermodynamic state due to the high free energy of Ag3Sn nanoparti-cles, which sporadically distribute in the matrix as second-phase. The second-phase Ag3Sn nanoparti-cles aggregate rapidly and grow to form bulk inter-metallic compounds due to the migration of grain boundary between primary Sn-rich phase and the Ag3Sn nanoparticles during high temperature aging treatment.The abnormal growth of Ag3Sn intermetallic compounds in eutectic Sn-3.5% Ag solder was investigated through high-temperature aging treatment. Microstructural evolutions of this solder before and after the aging treatment were observed by optical microscopy and scanning electron microscopy. Precise differential thermal analysis was made to study the changes in enthalpies of the solder under different conditions. The results reveal that the water-cooled solder is in metastable thermodynamic state due to the high free energy of Ag3Sn nanoparticles, which sporadically distribute in the matrix as second-phase. The second-phase Ag3Sn nanoparticles aggregate rapidly and grow to form bulk intermetallic compounds due to the migration of grain boundary between primary Sn-rich phase and the Ag3Sn nanoparticles during high temperature aging treatment.

关 键 词：无铅焊料 金属间化合物 示差热分析 纳米相 Ag3Sn 

分 类 号：TG42[金属学及工艺—焊接]