(大连理工大学 材料科学与工程学院，大连 116024)
摘 要: 采用浸焊方法制备Cu/Sn-58Bi/Ni线性焊点，研究5×103 A/cm2、170 ℃条件下液-固电迁移对Cu/Sn-58Bi/Ni线性焊点Cu、Ni交互作用以及界面反应的影响。无论电流方向如何，在液-固电迁移过程中焊点均表现为“极性效应”，即阳极界面金属间化合物(IMC)持续生长变厚，且一直厚于阴极界面的IMC。电迁移显著加快了Cu、Ni原子的交互作用。当电子由Ni流向Cu时，在化学势梯度和电子风力的耦合作用下，Ni原子扩散至阳极Cu侧参与界面反应生成(Cu,Ni)6Sn5类型IMC，同时一定量的Cu原子能够逆电子风扩散到Ni侧，参与界面反应生成(Cu,Ni)6Sn5类型IMC；当电子由Cu流向Ni时，大量的Cu原子扩散至Ni侧，并参与界面反应生成(Cu,Ni)6Sn5类型IMC，然而，Ni原子在逆电子风条件下无法扩散至Cu侧，从而使阴极Cu侧界面始终为Cu6Sn5类型IMC。此外，无论电流方向如何，焊点内都没有出现Bi的聚集。
关键字: 液-固电迁移；交互作用；Cu/Sn-58Bi/Ni焊点；界面反应；金属间化合物
（School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China）
Abstract:Cu/Sn-58Bi/Ni interconnect was prepared by dip-soldering, the effects of liquid-solid electromigration liquid-solid electromigration (L-S EM) on the Cu-Ni cross-solder interaction and the interfacial reaction in Cu/Sn-58Bi/Ni interconnects were investigated at current density of 5×103 A/cm2 and 170 ℃. Regardless of the current direction, a polarity effect is observed in Cu/Sn-58Bi/Ni interconnects undergoing liquid-solid electromigration (L-S EM), i.e., the interfacial intermetallic compound (IMC) at the anode grows continuously and is obviously thicker than that at the cathode. EM significantly enhances the interaction between Cu and Ni atoms. When electrons flow from Ni to Cu, the diffusion of Ni atoms are significantly enhanced by the combining effect of chemical potential gradient and electronic wind, resulting in the formation of (Cu,Ni)6Sn5 at the anode Cu interface, while a certain amount of Cu atoms diffuse to the Ni cathode interface under upwind diffusion, resulting in the formation of (Cu,Ni)6Sn5. When electrons flow from Cu to Ni, a large number of Cu atoms diffuse to the anode Ni interface, resulting in the formation of (Cu,Ni)6Sn5 IMC. However, Ni atoms are difficult to diffuse to the cathode Cu interface under upwind diffusion, thus, Cu6Sn5 IMC remains at the cathode. Furthermore, regardless of the current direction, Bi atoms do not segregate undergoing electromigration (EM).
Key words: liquid-solid electromigration; cross-solder interaction; Cu/Sn-58Bi/Ni interconnect; interfacial reaction; intermetallic compound
