A vialess vertical transition at millimeter wave frequencies

A vertical multilayer transition for millimeter wave frequencies is introduced. The transition is implemented in IMEC multi-chip-module technology using high resistive silicon and Benzo-Cyclo-Butene as base materials. As metalized vias in high resistive silicon are difficult to achieve, the transition is designed without using any vias. Simulation and measurement results for a back-to-back CPW-to-microstrip transition prototype show excellent agreement. Moreover, the microstrip-to-microstrip vertical via-less transition which is the core idea in this paper demonstrates less than 0.7 dB loss in the band from 57 GHz to 66 GHz. This property makes the proposed vertical via-less transition a valuable candidate for 60 GHz communications systems.