Modular interposer architecture providing scalable heat removal, power delivery and communicationCarrICool will deliver a game-changing 3D packaging platform for scale-up of future, many-core, Exascale computing systems. The project will also develop a strategic supplier base in Europe for high-end HPC components and systems integration capabilities in the Exascale era. In CarrICool, advanced More-than-Moore components required to scale to energy efficient ExaFLOP computing performance will be developed and integrated into a modular and multifunctional interposer. Four critical packaging elements are implemented on the CarrICool interposer: i) Improved structural and electrical performance will be provided by expansion matching and high wiring density. ii) low thermal gradients for Beyond-CMOS and silicon photonic devices will be provided by integrated, single-phase, water-cooling cavities. iii) High granularity, distributed Buck-converters using integrated, high-quality power inductors will support energy-efficient power delivery to heterogeneous chip stacks. iv) Off-chip bandwidth will be enabled through low-cost and low-loss passive optical coupling to silicon photonic wave guides. CarrICool is targeting 2-fold improvement in heat removal, 10-fold higher voltage granularity and a 10-fold cost reduction in photonic packaging.Advanced characterization and simulation techniques will be implemented using physics-of-failure-based lifetime modelling to provide design-rules for improved system architecture. The performance of the four packaging elements of the modular interposer will be validated on three separate demonstrators and then integrated on the main CarrICool demonstrator. The CarrICool consortium pools interdisciplinary excellence, uniting ten partners from global companies (2), European SMEs (3), institutes (3) and academia (2) across seven European countries. An Advisory Board ensures the alignment of the project goals with user needs.