Au-Sn焊点异质界面的耦合反应及其对力学性能的影响  

Coupling reaction at Au-Sn heterogenous interface joints and its effects on mechanical property

作　　者：朱学卫[1] 韦小凤[1] 黄玉祥[1] 卫启哲 程小利 ZHU Xuewei;WEI Xiaofeng;HUANG Yuxiang;WEI Qizhe;CHENG Xiaoli(College of Mechanical and Electronic Engineering, Northwest A & F University, Yangling 712100, China;Chongqing Materials research Institute Co. Ltd., Chongqing 400707, China)

机构地区：[1]西北农林科技大学机械与电子工程学院,陕西杨凌712100 [2]重庆材料研究院有限公司,重庆400707

出　　处：《中南大学学报（自然科学版）》2019年第4期821-828,共8页Journal of Central South University:Science and Technology

基　　金：陕西省科技攻关项目(2016NY-137);中央高校基本科研业务费专项基金资助项目(2452017132;2452016075)~~

摘　　要：为了探讨Au-Sn异质焊点耦合界面反应对界面IMC层生长行为及焊点力学性能的影响,采用回流焊技术制备Ni/AuSn/Ni和Cu/AuSn/Ni三明治结构焊点,通过扫描电子显微镜(SEM)与能谱分析(EDS)研究焊点在钎焊与老化退火中的组织演变。研究结果表明:在钎焊中Ni-Ni焊点的Au Sn/Ni界面形成(Ni,Au)_3Sn_2金属间化合物(IMC)层,而Cu-Ni焊点的AuSn/Ni界面形成(Ni,Au,Cu)_3Sn_2四元IMC层,表明钎焊过程中上界面的Cu原子穿过Au Sn焊料到达Ni界面参与耦合反应。在老化退火中,界面IMC层的厚度l随退火时间t延长而逐渐增大,其生长规律符合扩散控制机制的关系式:l=k(t/t_0)~n。在160℃和200℃退火时,(Ni,Au)_3Sn_2层的生长以晶界扩散和体积扩散为主。由于Cu原子的耦合作用,(Ni,Au,Cu)_3Sn_2层的生长以反应扩散为主。Cu-Ni异质界面焊点中,Cu的耦合作用抑制了Au Sn/Ni界面(Ni,Au,Cu)_3Sn_2IMC层的生长,减缓了焊点剪切强度的下降速度,有利于提高焊点的可靠性。In order to discuss the coupling effects on the growth behavior of intermetallic compounds (IMC) and mechanical property of joints, the Ni/AuSn/Ni (Ni-Ni) and Cu/AuSn/Ni (Cu-Ni) sandwich solder joints were prepared by reflowing process and isothermal aged at various solid-state temperatures. The interfacial reactions and microstructures of joints were investigated by scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The results show that, at as-reflowed joints, the ternary (Ni,Au) 3 Sn 2 phases are formed at the AuSn/Ni interface in Ni-Ni type joints, and he quaternary (Ni,Au,Cu) 3 Sn 2 phases are formed at the AuSn/Ni interface in Cu-Ni type joints. A coupling effect occurs at AuSn/Ni interfaces in Cu-Ni joints. During the isothermal aging, the thickness l of the IMC layers monotonically increase with increasing aging time t according to the relationship l=k(t/t 0 )^ n for both type joints. Aged at 160 ℃ and 200 ℃, the grain boundary diffusion as well as volume diffusion contributes to the rate-controlling process for the (Ni,Au) 3 Sn 2 layer. However, due to the coupling interfacial reaction with Cu atoms diffusion through the solder to the Ni side, the (Ni,Au,Cu) 3 Sn 2 layer was growing with reaction diffusion mechanism. The coupling effects in Cu-Ni type joints can inhibit the growth of (Ni,Au,Cu) 3 Sn 2 layer at AuSn/Ni interface, which can slow down the deterioration of 822 mechanical property, and improve the reliability of soldering joints.

关 键 词：AuSn 焊点 异质界面 耦合反应 界面金属间化合物(IMC) 生长行为 

分 类 号：TG156.21[金属学及工艺—热处理]