Developing solutions that provide high-bandwidth and low-energy communication has been at the forefront of interconnect and packaging research [1]. Within a module, the challenge has been addressed by using novel 2.5D (silicon interposer) and 3D stacking for short and high-density electrical interconnections and silicon photonics based interconnects. However, wafer-level batch fabricated solutions for high-bandwidth and low-energy interconnection between modules remain largely missing. Fig. 1 illustrates three approaches for package-to-package communication: through the motherboard, Flex connection [2], and using optical fibers. Electrical connectivity through the motherboard is both bandwidth limited and energy consuming. The use of Flex connection provides lower loss channels, however it requires a serial assembly process, which may limit its scalability. Methods involving optical fibers suffer the same limitation and are limited to relatively large interconnect pitches.
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