Microstructural Evolution and Growth Morphology During Formation Process of Full Cu₃Sn Solder Joint in Microelectronic Packaging

Abstract

The full Cu3Sn solder joint has been widely used in 3D packaging gradually. 270℃ and 1N were chosen as soldering temperature and pressure respectively to fabricate solder joints under different soldering time in order to analyze the process of microstructural evolution.Cu6Sn5 morphology with different soldering temperatures and time was also observed respectively to investigate the growth law of Cu6Sn5 and the effect of soldering temperature on the Cu6Sn5 morphology. The results show that scallop-like Cu6Sn5 is formed along the Cu substrate after 30min soldering, and a thin layer of Cu3Sn is generated between Cu6Sn5 and Cu substrate.When the soldering time is increased to 60min, liquid Sn is totally consumed and Cu6Sn5 becomes a cohesive whole. With the increase of soldering time, Cu3Sn grows at the expense of Cu6Sn5. Cu6Sn5 is totally transformed into Cu3Sn up to 480min. The growing process of Cu6Sn5 includes nucleation, growth, fusion and covering up the big grain. With the increase of soldering temperature, the morphology of Cu6Sn5 changes from polyhedron shape to procumbent.

Keywords

• Cu₃Sn solder joint
• Cu₆Sn₅
• microstructural evolution
• morphology