High performance vertical interconnections for millimeter-wave multichip modules

This paper presents high performance flip-chip and through-substrate via transition designs applicable in millimeter-wave single or multichip module assemblies. Full-wave electromagnetic analysis is performed to achieve an optimized transition topology. Interconnection test structures were fabricated in ceramic substrates and performance was successfully validated by on-wafer scattering parameter measurements up to 50 GHz. Both the flip-chip transition and the through-substrate via transition with a height of 800 μm exhibited return loss better than 25 dB and 20 dB, respectively, with very low transmission losses within the entire measured band.