界面耦合作用对Cu(Ni)/Sn-Ag-Cu/Cu(Ni)BGA焊点界面IMC形成与演化的影响

来源期刊：金属学报2011年第5期

论文作者：李勋平 周敏波 夏建民 马骁 张新平

文章页码：611 - 619

关键词：无铅焊点； 界面耦合； 金属间化合物； Kirkendall空洞； 剥离现象

Key words：lead-free solder joint； cross-interaction of interface； intermetallic compounds； Kirkendall void； spalling phenomenon

摘    要：

研究了焊盘材料界面耦合作用对Cu(Ni)/Sn-3.0Ag-0.5Cu/Cu(Ni)BGA(Ball Grid Array)结构焊点焊后态和125℃等温时效过程中界面金属间化合物(IMC)的成分、形貌和生长动力学的影响.结果表明.凸点下金属层(UBM)Ni界面IMC的成分与钎料中Cu含量有关,钎料中Cu含量较高时界面IMC为(Cu.Ni)6Sn5.而Cu含量较低时,则生成(Cu,Ni)₃Sn₄;Cu-Ni耦合易导致Cu/Sn-3.0Ag 0.5Cu/Ni焊点中钎料/Ni界面IMC异常生长并产生剥离而进入钎料.125℃等温时效过程中.Sn-3.0Ag-0.5Cu/Cu界面IMC的生长速率常数随钎料中Cu含量增加而提高.Cu Cu耦合降低一次回流侧IMC生长速率常数;Cu Ni耦合和Ni-Ni耦合均导致焊点一次回流Ni侧界面IMC的生长速率常数增大,但Ni对界面IMC生长动力学的影响大于Cu;Ni有利于抑制Cu界面Cu₃Sn生长.降低界面IMC生长速率,但Cu-Ni耦合对Cu界面Cu₃Sn中Kirkendall空洞率无明显影响.

Abstract: The formation and evolution of interfacial intermetallic compounds (IMCs) in Cu(Ni)/Sn-3.0Ag-0.5Cu/Cu(Ni)BGA (Ball Grid Array) structure solder joints both in the asreflowed state and undergoing isothermal aging at 125℃ were investigated.The results show that there exists a significant cross-interaction effect of the solder pad/under bump metal( UBM) on the composition,morphology and growth kinetics of interfacial IMCs in solder joints.The reactions of solder/Ni UBM strongly depends on the Cu content of the solder,for a high Cu content,a continuous (Cu,Ni)₆Sn₅ layer forms at the interface,while for a low Cu content,a continuous(Ni,Cu)₃Sn₄ layer appears at the interface.The cross-interaction of Cu and Ni in Cu/Sn 3.0Ag-0.5Cu(SAC)/Ni solder joints has obvious influence on the composition and morphology of the interfacial IMC:and the IMC spalling phenomenon occurs at the interface of Ni side.During isothermal aging at 125℃,the growth rate constant of the interfacial IMC layer in SAC/Cu and Cu/SAC/Cu joints increases with the Cu concentration, and the cross-interaction of Cu and Cu decreases the interfacial IMC growth rate constant at once-reflowed Cu side.However,both of the cross-interactions of Cu-Ni and Ni-Ni increase the growth rate constant of the interfacial IMC at once reflowcd Ni side and Ni has a greater influence than Cu.The cross-interaction of Cu and Ni is beneficial for suppression of growth of Cu₃Sn and reduction the growth rate of IMC at Cu side,while having no significant influence on the porosity of Kirkendall voids in Cu₃Sn layer at Cu side of the joint.