Process Development of Fan-Out interposer with Multi-layer RDL for 2.5D System in Package

In this paper, the fabrication process flow and results of a Fan out interposer for 2.5D system in package were presented. The Fan-out interposer can replace conventional through silicon interposer with reduction in both package size and cost. Fan-out interposer package has a 30 x 25 mm(2) package size which includes four layers of redistribution layers (RDLs) and 200 mu m thick epoxy mold support and Cu pillars through Mold Interconnections (TMIs). High density, fine pitch Cu RDL was used to provide connection to the large number of channels between an ASIC and two high bandwidth memory chips. RDL-first integration flow was used to fabricate the fan-out interposer using a laser de-bonding technique. The fan-out interposer fabrication process and the assembly process of chips and board assembly were demonstrated.