Fan-out packaging addresses several challenges with traditional packaging. These include direct assembly to system substrates and boards, while eliminating off-chip solder interconnects with large stand-off heights, along with minimizing wafer bumping needs. In addition, fan-out packaging offers superior electrical performance, along with the ability to extend to 3D package stacking for vertical system integration. For low Input/Output (I/O) termination counts between the chip and substrate, additively-deposited fan-out interconnects are of high interest. Traditional approaches are based on silver paste or ink deposits for interconnects. We investigate solder-graphene composite-based fan-out interconnects as an alternative to silver. To facilitate solder trace formation on polymer gap-fill, graphene network loading is introduced into the solders. Initial process development demonstrated the feasibility of forming such interconnects. This material system also plays a strategic role in phase-change materials for heat spreading, electromagnetic interference shielding, and other applications. The second part of the paper describes innovative multiscale fan-out packages with solder composite-based interconnects, extending today's glass- or laminate-based panel fan-out packages.
