An Ultrawideband Microcoaxial Load via Copper Micromanufacturing and Flip-Chip Assembly

作者：Jia Wen, Xiaozhu Wen, Zhen Wang, Tingting Sun, Ming Guo, Yongmao Sun, Zhou Chen, Guanghua Shi, Cheng Guo · 发表于：IEEE Microwave and Wireless Technology Letters · 年份：2025 · DOI：10.1109/lmwt.2025.3624021 · 研究领域：Microwave and Dielectric Measurement Techniques、Electrical and Thermal Properties of Materials、Radio Frequency Integrated Circuit Design

This letter presents an ultrawideband microcoaxial load inspired by the on-chip short-open-load-thru (SOLT) calibration standard. The design integrates thin-film resistors on a quartz substrate with a microcoaxial package fabricated using copper-based micrometal additive manufacturing (M-MAM). A L-type equivalent network is implemented to realize broadband impedance matching between the resistors and the microcoaxial transmission line, and a flip-chip assembly is adopted to minimize parasitic effects. Two testing interfaces are designed for characterization: a$125~\mu $m-pitch GSG interface and a 1-mm connector-compatible interface. Simulation results indicate return loss better than 20 dB up to 150 and 133 GHz, respectively. Measurements both show over 20 dB return loss up to 90 GHz and over 15 dB at 110 GHz. The proposed compact load offers excellent and consistent performance, supporting integration into broadband RF components and high-precision instrumentation systems.