The flip-chip approach for millimeter wave packaging

A particularly critical issue in this regard is module packaging, i.e., the way to assemble and connect several monolithic microwave integrated circuits (MMICs) in a multichip environment in order to build the millimeter-wave front-end. The requirements on the packaging scheme are obvious: the interconnects should provide good millimeter-wave performance (primarily meaning: low reflections and low insertion loss) and, at the same time, they should allow for low-cost fabrication. Among the multichip packaging techniques available, the flip-chip approach is considered to be the most promising candidate to meet these requirements.