(大連理工大學 材料科學與工程學院，大連 116024)
摘 要: 采用浸焊方法制備Cu/Sn-58Bi/Ni線性焊點，研究5×103 A/cm2、170 ℃條件下液-固電遷移對Cu/Sn-58Bi/Ni線性焊點Cu、Ni交互作用以及界面反應(yīng)的影響。無論電流方向如何，在液-固電遷移過程中焊點均表現(xiàn)為“極性效應(yīng)”，即陽極界面金屬間化合物(IMC)持續(xù)生長變厚，且一直厚于陰極界面的IMC。電遷移顯著加快了Cu、Ni原子的交互作用。當電子由Ni流向Cu時，在化學勢梯度和電子風力的耦合作用下，Ni原子擴散至陽極Cu側(cè)參與界面反應(yīng)生成(Cu,Ni)6Sn5類型IMC，同時一定量的Cu原子能夠逆電子風擴散到Ni側(cè)，參與界面反應(yīng)生成(Cu,Ni)6Sn5類型IMC；當電子由Cu流向Ni時，大量的Cu原子擴散至Ni側(cè)，并參與界面反應(yīng)生成(Cu,Ni)6Sn5類型IMC，然而，Ni原子在逆電子風條件下無法擴散至Cu側(cè)，從而使陰極Cu側(cè)界面始終為Cu6Sn5類型IMC。此外，無論電流方向如何，焊點內(nèi)都沒有出現(xiàn)Bi的聚集。
關(guān)鍵字: 液-固電遷移；交互作用；Cu/Sn-58Bi/Ni焊點；界面反應(yīng)；金屬間化合物
（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
