Alloying Modification of Low-Ag-Content Sn-Ag-Cu Solders

Sn-Ag-Cu (SAC) alloy is currently recognized as the standard lead-free solder alloy for packaging of interconnects in the electronics industry and high- Ag-content SAC alloys are the most popular choice. However this choice has been encumbered by the fragility of the solder joints that has been observed in drop testing as well as the high cost of the Ag itself. Therefore low-Ag-content SAC alloy was considered as a solution for both issues. However this approach may compromise the thermal-cycling performance of the solders. Therefore to enhance the thermal-cycling reliability of low-Ag-content SAC alloys without sacrificing their drop-impact performance alloying elements such as Mn Ce Ti Bi In Sb Ni Zn Al Fe and Co were selected as additions to these alloys. However research reports related to these modified SAC alloys are limited. To address this paucity the present study reviews the effect of these minor alloying elements on the solder joint reliability of low-Ag-content SAC alloys in terms of thermal cycling and drop impact.