Effect of Multiple Reflow Processes on the Reliability and Microstructure of Sn-Ag-Cu-In Solder Joint

초록

The authors have previously reported that the quaternary Sn-1.2Ag-0.7Cu-0.4In(wt%) alloy showed excellent wettability and mechanical reliability. Moreover, the addition of small amount of Pd or Mn was considered to improve its reliability to a greater extent especially in drop impact condition. In this study, the effect of multiple reflow processes on the drop impact reliability and microstructure of Sn-1.2Ag-0.7Cu-0.4In-X solder joints was investigated. The test package was prepared with OSP (organic solderability preservative)/Cu finished FR-4 PCD and ENIG finished BGA package. After the first reflow, the samples were repeated reflow of 3 and 5 cycles. The drop impact reliability tests were performed in a various ways and the results were compared with those of Sn-1.0Ag-0.5Cu and Sn-3.0Ag-0.5Cu alloys. The microstructure and partitioning of alloying elements in the solder joint were analyzed using SEM, EDS, XRD, EPMA and XPS.