Akademik Veri Yönetim Sistemi
IEEE Microwave and Wireless Technology Letters, 2026 (SCI-Expanded, Scopus)
Accurate characterization of underfill dielectric properties is critical for millimeter-wave (mm-wave) flip-chip packaging, as dielectric loss can significantly degrade high-frequency performance. In this letter, the frequency-dependent electrical permittivity and loss tangent of an epoxy-based underfill are extracted via transmission/reflection method using a WR-28 filled waveguide. Then, the extracted material properties are directly incorporated into a full-wave FEM model of a flip-chip packaged transmission structure without any fitting or tuning parameters and confirmed with measurements. To validate the approach at the package level, custom-designed flip-chip packaged substrate and dedicated thru–reflect–line (TRL) calibration kits are fabricated, enabling accurate S-parameter measurements from 10 to 40 GHz. Excellent agreement between simulated and measured results, both with and without underfill, confirms the accuracy of the proposed characterization method and highlights the dominant impact of underfill dielectric loss on mm-wave package performance.