Structure Analysis of Solder Ball Joint Interface on Electroless Ni-B with Immersion Au deposition

Abstract

Three types of solder ball (Sn-37Pb, Sn-3.5Ag-0.75Cu and Sn-8Zn-3Bi) were jointed on a substrate (Au/Ni-B) which was deposited by electroless Ni-B alloy plating with immersion Au plating processing. The jointing strengths of each solder alloy on Au/Ni-B were measured by the heating-type single-bump pull test. The boundary layer of each solder alloy on Au/Ni-B was analyzed using a SEM and EPMA. It was found that each intermetallic compound of the Ni-Sn, Cu-Ni-Sn and Au-Zn systems was formed along the interfaces between each type of solder and the Au/Ni-B and that these jointed each solder alloy to the Au/Ni-B. Also, enrichment of the B content in the Ni-B alloy film was caused along the jointing phase boundary by the jointing of Sn-37Pb and Sn-3.5Ag-0.75Cu solders.