(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 研究微量稀土La在钎焊和时效过程中对Sn-3.0Ag-0.5Cu无铅钎料与铜基板的钎焊界面及钎料内部金属间化合物(IMC)的形成与生长行为的影响。结果表明：钎焊后钎焊界面形成连续的扇形Cu6Sn5化合物层，其厚度随La含量的增加而减小；在150 ℃时效100 h后，连续的Cu3Sn化合物层在Cu6Sn5化合物层和铜基板之间析出，且Cu6Sn5层里嵌有Ag3Sn颗粒；界面金属间化合物总厚度随时效时间的延长而增厚，且在相同时效条件下随La含量的增加而减小；时效过程中金属间化合物生长动力学的时间系数(n)随着La含量的增加逐渐增大；钎焊后钎料内部Ag仍以共晶形式存在，时效后Ag3Sn颗粒沿钎料内部的共晶组织网络析出。
关键字: Sn-Ag-Cu无铅钎料；La；钎焊；时效；金属间化合物
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effects of minor La on the formation and growth behaviors of intermetallic compounds at Sn-3.0Ag-0.5Cu lead-free solder alloy/copper substrate interface and inside the solders during soldering and aging were investigated. The results show that Cu6Sn5 layer formed at the interface exhibits a continuous scallop-shaped structure after soldering, the thickness of Cu6Sn5 layer decreases with increasing La content. A thin Cu3Sn intermetallic compounds layer forms at the interface between Cu6Sn5 layer and Cu substrate after aging at 150 ℃ for 100 h. Ag3Sn particles are embedded to the Cu6Sn5 layer. The total intermetallic compounds thickness increases with prolonging aging time, and decreases with increasing La content under the same aging condition. The time exponent (n) in growth kinetic of intermetallic compounds layer during aging increases with increasing La content. Ag elements exist in Sn-Ag eutectic structures after soldering, and Ag3Sn particles are precipitated along the eutectic bonds after aging.
Key words: Sn-Ag-Cu lead-free solder; La; soldering; aging; intermetallic compound
