Effect of NCFs with Zn-nanoparticles on the interfacial reactions of 40 um pitch Cu pillar/Sn-Ag bump for TSV interconnection

NCFs with Zn-nanoparticles of different resin acidity, resin viscosity, resin curing speed were formulated, and diffused Zn contents in the solder bumps were measured after reflow. Amount of Zn diffusion into the solder bumps increased as resin acidity increased, as resin viscosity decreased, as curing speed decreased, and as reflow temperature increased. Diffusion of Zn nano-particles into the solder bumps are maximized when flow-able resin viscosity and break of oxides are achieved. To analyze the effect of Zn on IMC reduction, NCFs with 0 wt%, 1 wt%, 5 wt%, and 10 wt% of Zn nano-particles were bonded on the test vehicles, and aged at 150°C up to 500 hours. NCF with 10wt% Zn nano-particle showed remarkable suppression in Cu₆Sn₅ and (Cu, Ni)₆Sn₅ IMC compared to NCFs with 0 wt%, 1 wt%, and 5 wt% of Zn nano-particles. However, in terms of Cu₃Sn IMC suppression, NCFs with 1 wt%, 5wt%, and 10wt% showed an equal amount of IMC suppression.