60 GHz Broadband MS-to-CPW Hot-Via Flip Chip Interconnects

In this letter, the microstrip-to-coplanar waveguide (MS-to-CPW) hot-via flip chip interconnect has been experimentally demonstrated to have broadband performance from dc to 67 GHz. The interconnect structures with the hot-via transitions were first designed and optimized by using the electromagnetic simulation tool. Three types of designs were investigated in this letter. The interconnect structures were then fabricated and radio frequency (RF) tested up to 67GHz. The optimized interconnect structure with the compensation design demonstrated excellent RF characteristics with the insertion loss less than 0.5dB and the return loss below 18dB over a very broad bandwidth from dc to 67GHz. This is to our knowledge the best result reported for this frequency range.