Growth kinetics of the Cu3Sn phase and void formation of sub-micrometre solder layers in Sn–Cu binary and Cu–Sn–Cu sandwich structures.

Highlights: [•] Sub-micron solder thickness Cu/Sn/Cu sandwich structure and Sn/Cu binary samples were studied by reflow and aging, to explore the unique “solder-depletion” phenomenon. [•] The “Cu6Sn5 consumption based” Cu3Sn growth was also studied, and it showed very different growth rate and characteristics. [•] Optimized thickness for ultra-thin solder layer interconnection were studied by experiments. Formation of micro-voids was observed and discussed. [•] Effects of acid cleaning (before electroplating) on the microstructures was also discussed. [Copyright &y& Elsevier]