Broadband Dielectric Properties of Integrated Circuit Packaging Materials Across the 6G Spectrum

Abstract

In the United States, the Federal Communications Commission has authorized experimental licenses in the electromagnetic frequency range from 95 GHz to 3 THz to develop wireless technologies beyond the current 5G. The initial rollout of 6G is expected to use the lower end of this spectrum from 95 to 300 GHz. Development of commercially viable 6G electronic hardware still poses many unanswered challenges ranging from improving integrated circuit performance to miniaturization of passive components to packaging of circuits and components. Packaging designs are currently limited by a lack of knowledge of the dielectric properties of commonly used packaging materials. The 6G spectrum is high enough in frequency that assuming the continued validity of radio frequency (RF) or microwave dielectric property values is no longer warranted. Here, we present the results of permittivity, Dk, and dissipation factor (loss tangent), Df, measurements at 23 °C and 150 °C on 15 commercial materials now used to package RF/microwave circuits. Measurements used phase-sensitive transmission from 90 to 325 GHz. Dk ranged from 1.1 to 4.5 with negligible or small temperature dependencies. Df ranged from 0.01 to 0.04 and was generally 2–3 times higher at 150 °C compared to 23 °C. The results are meant to be useful inputs to model the normal performance of packaged 6G circuits.