By TSMC (Taiwan Semiconductor Manufacturing Company)
CoWoS®-R advanced packaging service achieves heterogeneous integration by using a redistribution layer (RDL) interposer as the interconnect between System-on-Chip (SoC) and/or high-bandwidth memory (HBM), having been in volume production since 2023. An RDL interposer is comprised of polymer and copper traces and is relatively flexible. This enhances C4 joint integrity and allows the package to scale to meet very complex functional demands. Key CoWoS®-R features include: 1. An RDL interposer for routing, with a minimum 4μm pitch (i.e., 2μm line width/spacing). 2. An RDL interconnect offers good signal and power integrity with a lower RC value routing line to achieve a high data transmission rate. The co-planar Ground-Signal-Ground-Signal-Ground (GSGSG) and interlayer ground shielding with RDL interconnections offer superior electrical performance. 3. RDL layer and C4/underfill (UF) layers provide an excellent buffer thanks to the coefficient of thermal expansion (CTE) mismatch between an SoC and the corresponding substrate. The strain energy density is greatly reduced in C4 bump area.
