稀土元素Eu对SnAgCu钎料组织与性能影响  

Microstructures and Properties of SnAgCu Solder Doped with Eu

作　　者：张亮 Tu King Ning 郭永环[1] 何成文[1] 

机构地区：[1]江苏师范大学机电工程学院 [2]江苏科技大学先进焊接技术省级重点实验室 [3]Department of Materials Science and Engineering,University of California,Los Angeles CA90024,USA

出　　处：《稀有金属》2015年第1期11-15,共5页Chinese Journal of Rare Metals

基　　金：江苏省自然科学基金项目(BK201244);江苏省高校自然科学基金项目(12KJB460005);江苏科技大学先进焊接技术省级重点实验室开放研究基金项目(JSAWS-11-03);江苏师范大学自然科学研究基金项目(11XLR16)资助

摘　　要：研究了稀土元素Eu对SnAgCu无铅钎料组织与性能的影响。结果表明:微量的稀土元素Eu可以显著提高无铅钎料在铜基板表面的润湿性和QFP256器件无铅焊点力学性能,稀土的最佳添加量为0.04%左右;当稀土元素含量高于0.04%,无铅钎料的铺展面积和无铅焊点拉伸力均明显下降;对钎料的基体组织研究发现稀土元素的添加可以显著细化β-Sn基体组织,金属间化合物颗粒尺寸也明显减小。同时在150℃时效(1000 h)过程中,SnAgCu和SnAgCu-0.04Eu两种钎料的基体组织均发生明显的粗化,特别是Cu6Sn5颗粒明显较为粗大;但是相对SnAgCu钎料,SnAgCu-0.04Eu钎料的组织粗化程度明显较小。稀土元素添加过量时,钎料的润湿性、力学性能明显恶化,基体组织出现明显的锡须,添加微量稀土Eu时,并未发现锡须。含稀土SnAgCu钎料表面生长锡须,可以采用"氧化膜破裂机制"解释这种现象,稀土相因为氧化体积明显增大,那么内部就会产生较大的压应力,压应力即为锡须生长的驱动力。The effect of rare earth Eu on the microstructures and properties of SnAgCu solder was investigated. The results indicated that small amount of rare earth Eu could markedly improve the wettability of solders on Cu substrate and the tensile force of solder joints,and the optimum content of rare earth Eu was around 0. 04%. When the Eu content was higher than 0. 04%,the spreading area of lead-free solders and tensile force of solder joints decreased obviously. Based on the analysis of microstructure of SnAgCu,it was found that the microstructure of solder matrix could be markedly refined with the addition of rare earth Eu,meanwhile,the size of intermetallic compound particles could be reduced,too. During 150 ℃ isothermal aging（1000 h）,the coarsening of SnAgCu and SnAgCu Eu solder occurred obviously,especially for the Cu6Sn5 phase. Compared with the microstructure of SnAgCu solder,the coarsening of the SnAgCu Eu solder microstructure was not that obvious. However,with excessive rare earth Eu added,the wettability of solders and the tensile force of the solder joints were both deteriorated significantly,and the whiskers could be found in the matrix microstructure. However,small amount of Eu did not result in the whiskers. The oxidation mechanism could be used to explain the whisker growth of SnAgCu solders bearing rare earth; the volume of RE-rich phase expanded due to oxidation,which would result in compressive stress which was the driving force of whiskers.

关 键 词：无铅钎料 润湿性 力学性能 锡须 

分 类 号：TG454[金属学及工艺—焊接]