The effect of indium and bismuth addition on IMC formation of SN 96AG 3.5CU 0.5 solder
Abstract
This work focused on the effect of adding indium and bismuth to wettability and the IMCs that form at the surface before and after aging to the ternary Sn 96Ag 3.5Cu 0.5 solder. Solders (SAC-9In and SAC- 5In4Bi) were prepared by melting the components together at 500°C. Solders were then re-flowed on Cu substrate at temperature 20°C and 40°C above melting point for each solder. The microstructural characteristics of IMCs formed at solder joint before and after aging were carried out using Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-Ray (EDX). The DSC result shows that the melting point of SAC solder was reduced from 217°C to 202°C and 214°C with addition of 9% In and 4% Bi respectively. Adding In increases F max and lower wetting time and thus indicates better wettability. Addition of Bi results in lower thickness of IMC and this indicates better reliability of solder joint.
