纳米锑掺杂对回流焊Sn-3.0Ag-0.5Cu-xSb焊点界面IMC生长的影响机理  

Influence of nano-Sb dopant on IMC growth in Sn-3. 0Ag-0. 5Cu-xSb solder joints in reflow process

作　　者：唐宇[1,2] 潘英才[2] 李国元[2] 

机构地区：[1]仲恺农业工程学院自动化学院,广州510225 [2]华南理工大学电子与信息学院,广州510641

出　　处：《焊接学报》2014年第1期95-100,117-118,共6页Transactions of The China Welding Institution

基　　金：中央高校基本科研业务费专项资金项目(2014ZB0032);广东省科技计划资助项目(2012B020313004);广东高校优秀青年创新人培养计划资助项目(LYM11077)

摘　　要：研究了纳米锑掺杂对回流焊过程中Sn-3.0Ag-0.5Cu-xSb(x=0,0.2%,1.0%和2.0%)焊点界面金属间化合物(IMC)生长动力学的影响.借助扫描电镜(SEM)观察了焊点的微观结构,利用X射线能谱分析(EDX)及X射线衍射谱仪(XRD)确定了IMC的相和成分.结果表明,部分纳米锑颗粒溶解在富锡相中形成SnSb二元相,部分纳米锑颗粒溶解在Ag3Sn相中形成Ag3Sb相,剩余部分沉降在界面Cu6Sn5金属间化合物层表面.随着纳米锑含量的增加,IMC厚度减小.当纳米锑的含量为1.0%时,IMC厚度最小.通过曲线拟合,确定出界面IMC层生长指数和扩散系数.结果表明,IMC层生长指数和扩散系数均随着纳米锑含量的增加而减小.当纳米锑的含量为1.0%,IMC层生长指数和扩散系数均有最小值,分别为0.326和10.31×10-10cm2/s.由热力学相图和吸附理论可知,Sn,Sb元素之间易形成SnSb化合物,引起Sn元素的活性、Cu-Sn金属间化合物形成的驱动力和界面自由能下降,从而导致Cu6Sn5金属间化合物生长速率下降,抑制IMC生长.The effect of nano-Sb addition on the growth kinetics of intermetallic compound( IMC) in the joints with Sn-3. 0Ag-0. 5Cu-xSb( x = 0,0. 2,1. 0,and 2. 0%) solder in reflow process was investigated. Scanning electron microscope( SEM) was used to observe the microstructure evolution of soldered joints,energy dispersive X-ray( EDX) and x-ray diffractometer( XRD) were used to identify the IMC phases. The results show that some nano-Sb particles were dissolved in Sn-rich phase,some participated in the formation of Ag 3 Sb,and the rest dissolved in Cu 6 Sn 5 IMC layer. The thickness of IMC layer decreased when the nano-Sb was added. Under the isochronal conditions,the thickness of IMC layer in all soldered joints was minimum when the amount of nano-Sb increased to about 1. 0%. The growth exponent n and diffusion coefficient D for IMC layer were determined by curve-fitting. The results reveal that the growth exponent n and diffusion coefficient D decreased with the increase of nano-Sb content. When the amount of nano-Sb increased to about 1. 0%,the growth exponent n and diffusion coefficient D were 0. 326 and 10. 31 × 10-10cm2/ s,respectively. Based on the phase diagram analysis and adsorption theory,Sb had better affinity to Sn,and it could reduce the activity of Sn by forming SnSb compound,resulting in decreased driving force and surface energy for formation of Cu-Sn IMC. Therefore, the growth rate of Cu 6 Sn 5 grains was suppressed and the growth of IMC layer was retarded.

关 键 词：回流焊 纳米掺杂 无铅焊料 金属间化合物 

分 类 号：TG425[金属学及工艺—焊接]