Interfacial reactions and compound formation in the edge of pbsn flip-Chip solder bumps on Ni/Cu Under-Bump Metallization

摘要

Flip-chip technology with the layout of ball grid array has been widely used in today's microelectronics industry.The elemental distribution in hte edge of the solder bump is crucial for its correlation with the bump strength.In this study,Ni/Cu under-bump metallization (UBM)was used to evaluate the intermetallic compoiund (IMC)formation in the edge of the solder bump between the UBM and eutectic Sn-Pb solder in the 63Sn-37Pb/Ni/Cu/Ti/Si_3N_4/Si multilayer structure.During reflows layered-type (Ni_(1-x)Cu_x)_3Sn_4 and island-like (Cu_(1-x)Ni_y)_6Sn_5 IMC_5 formed in the interface between the solder and UBM,while only the (Cu_(1-y)Ni_y)Sn_5 IMC was observed in the sideway of the Ni/Cu UBM.After high-temperature storage (HTS)at 150 deg C for 1,000 h,both (Cu_(1-y)Ni_y)_6Sn_5 and (Cu_(1-z)Ni_z)_3Sn were found in the sideway of the Ni/Cu UMB.Two other IMCs,(Ni_(1-x)Cu_z)_3Sn were found in the sideway of the Ni/Cu UBM.Two other IMCs,(Ni_(1-x)Cu_x)_3Sn_4 and (Cu_(1-y)Ni_y)_6Sn_5,formed in the interface between the solder and UBM.The growth of the (Cu_(1-y)Ni_y)_6Sn_5 IMC was relatively fast during HTS.