UCIe

Overview

UCIe (Universal Chiplet Interconnect Express) is an open industry standard for die-to-die (D2D) interconnects within chiplet packages. It defines the physical layer, link layer, and software stack for connecting chiplets across advanced packaging substrates (2.5D interposers, 3D stacking). Two variants exist: UCIe Standard (for longer reach with relaxed density) and UCIe Advanced (high-bandwidth short-reach for tightly integrated chiplets).

Rebellions' REBEL-Q uses UCIe Advanced for interconnecting four REBEL_H NPU chiplets, delivering 4 TB/s total D2D bandwidth (3 TB/s per chiplet channel). The same UCIe standard interconnects the Arm Neoverse V3 CPU chiplets and REBEL_H NPU chiplets in the four-party AI CPU chiplet platform. UCIe's open nature enables multi-vendor chiplet compositions without proprietary lock-in.