Process Developments on Sheet Molding and Redistribution Deposition for Cu-Pillar Chips

Drivers for 3D packaging solutions are increasing constantly. This work investigated a new interconnect technique using sheet molding process to enable Package-on-Package (PoP) stacking. This technique is based on sheet molding compound (SMC), which is suitable for multi-layer structures, thin and large area packaging. With the assist of vacuum, multiple singulated thinned Cu-pillar chips could be embedded in the sheet mold, to enable panel-level-packaging or wafer-level packaging following the mold-first approach. In this work, the feasibility of replacing the conventional epoxy-based molding compound (EMC) by SMC is investigated by experiments on different Cu-pillar standoffs and pitches. Furthermore, shear test of Cu buttons 200 $\mu {{\mathrm m}}$ in diameter and $40 \mu {\mathrm m}$ in height is carried out to determine the adhesion of the deposited layer on the SMC surface.