Determining Carbon Fiber Composite Loading with Flip-Chip Measurements to 110 GHz

Precise knowledge of electrical properties of materials are a necessary input to any circuit design. As applications at millimeter-wave frequencies increase, there is a need to develop new materials with low loss and multiple functionalities. Most material characterization techniques are destructive to the original sample. For example, most resonant cavity techniques require a sample to be diced into a submillimeter geometry. Alternatively, broadband on-wafer techniques require lithographically patterned devices on the material under test. Here, we demonstrate a technique that combines on-wafer calibration with a flip-chip transmission-line test fixture. This single-trans mission-line fixture enables quantitative measurement of effective permittivity from 40 kHz to 110 GHz. The resulting materials characterization approach is non-destructive and directly applicable to measurements of dielectric, magnetic, and nonlinear properties. The broad applicability of the technique makes it well-suited for characterizing the next generation of materials, including tunable materials and complex structural composites.