Development of sub-mm wave flip-chip interconnect

With the increasing availability of MMICs at high frequencies beyond 100 GHz low-loss interconnects for module fabrication become essential. This work presents the results of the flip-chip interconnects approach exhibiting bandwidths from 220 GHz up to 500 GHz. Flip-chip transitions in this study were fabricated based on simulated 3D models in three different topologies: coplanar-to-coplanar, stripline-to-coplanar, and stripline-to-stripline. The interconnects were realized with 10 µm-diameter AuSn microbumps. After the flip-chip mounting, scattering parameter measurements were performed to characterize the interconnect quality. The results suggest that the flip-chip technology is currently the most suitable technology for the high frequency range.