材料期刊网

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.

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 as-reflowed 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-reflowed 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.